More than one in ten Australian families with dependent children is now a blended family. Yet most financial and estate planning is still built on a model that assumes a single marriage, shared children and a simple path: everything goes to the surviving spouse, and eventually to the kids.
Apply that model to a blended family and it fails in a specific, predictable way. The surviving spouse inherits everything. They later remarry, or update their will, or simply spend the money. And the children of the first marriage, the ones the deceased assumed would eventually inherit, receive nothing at all. The family wealth moves sideways into a different bloodline.
It’s a common enough outcome to have a name: the sideways inheritance trap. And it’s one of several ways blended family finances go wrong, not through malice, but through planning that was never designed for the family that actually exists.
This guide explains the risks unique to blended families, the structures that protect everyone’s interests, and how to approach it fairly.
Note: estate structures must be drafted by a qualified solicitor. This is general information about the financial planning dimensions, not legal advice.
Why Blended Families Need a Different Estate Plan Approach
A traditional will, “everything to my spouse, then to my children”, works when both spouses share the same children. In a blended family, that structure quietly creates competing interests:
A new spouse who needs financial security, and possibly a home to live in, for the rest of their life.
Children from a previous relationship who may fear being cut out, and who often expect to inherit assets built before the new relationship existed.
Stepchildren, who may be close as family but have no automatic legal standing.
Sometimes a former spouse, with continuing obligations from a property settlement.
Each of these people has a legitimate claim on your care. The problem is that a simple will can only serve one of them at a time, and it usually chooses the spouse by default. Balancing them requires deliberate structuring, not a standard template.
The Sideways Inheritance Trap
This is the single most important risk to understand. If you leave your entire estate to your new partner, trusting they’ll pass it to your biological children when they die, you’re relying on something you can’t control. After your death, your current partner may:
Enter a new marriage, which in most Australian jurisdictions can revoke an existing valid will
Change their will to favour their own children or a new partner, including a de facto partner
Spend the assets during their lifetime, leaving nothing behind
None of these are unreasonable choices for them to make. But the outcome is that wealth built during your first marriage ends up outside your children’s hands entirely. If there is no valid will, the estate may instead be distributed under intestacy laws, creating unintended consequences for children and partners alike. Handshake agreements and good intentions are not a plan. Protecting your children requires legal structure.
Four Structures, Including Testamentary Trusts, That Protect Competing Interests
The good news is that you don’t have to choose between your partner and your children. Several structures let you provide for both.
Testamentary trust. A trust created by your will that activates on your death. It can provide income to your surviving spouse for their lifetime, while preserving the capital for your children to receive afterwards. It also gives you control over asset distribution, including directing specific assets to chosen beneficiaries and clearly identifying the ultimate beneficiaries once the trust ends. It offers asset protection and significant tax advantages, including concessional tax rates for minor beneficiaries, and it’s widely regarded as one of the key strategies in blended family estate planning.
Life interest or right to reside. Your spouse gets the legal right to live in the family home, or receive income from investments, for their lifetime or until a specified event such as remarriage, which may also revoke an existing will and leave the estate exposed to intestacy laws if no new will is made. In that arrangement, the spouse is effectively the life tenant. On their death, the property passes automatically to your biological children. It never becomes part of your spouse’s estate. A life interest is a stronger right than a right to reside, but usually comes with property maintenance obligations.
Mutual wills. A legally binding agreement between partners that neither will change their will after the first dies. If the survivor breaks it, a court can impose a constructive trust to protect the original beneficiaries. They offer certainty, but they’re rigid, and they can leave a surviving spouse unable to adapt to genuinely changed circumstances. Many advisers consider testamentary trusts the more flexible option as part of a comprehensive estate plan.
Immediate gifts and ownership structure. Rather than making children wait, you can leave them a direct gift. Crucially, property ownership determines whether your will controls it at all. Assets held as joint tenants pass automatically to the surviving owner and never enter your estate. Held as tenants in common, your share forms part of your estate and can be left to your children. For families planning for blended families, this single distinction can decide whether your children inherit anything.
The Superannuation Blind Spot
Here is where blended family planning most often collapses, and these are key strategies within a comprehensive estate plan for blended family estate planning.
Superannuation does not automatically follow your will. It does not automatically form part of deceased estates because it’s paid by your fund’s trustee, and without a valid binding death benefit nomination, the trustee decides who receives it. In a blended family, that is an invitation to dispute, delay, and an outcome you never intended. Given super is often one of the significant assets a person owns, and frequently carries life insurance policies, this is not a footnote.
Two practical points:
Super death benefits can generally only be paid to a spouse, children (including stepchildren in some circumstances), someone in an interdependency relationship, a financial dependant, or your estate. If you want super to reach someone outside those categories, or to flow into a testamentary trust, you must nominate your legal personal representative so the estate plan can direct those benefits to the intended beneficiaries.
Many binding nominations lapse after three years. A nomination made before a divorce or a new relationship may now direct your super to entirely the wrong person. Review them after every major life change.
Life insurance held outside super carries the same issue: it’s governed by its own beneficiary nomination, not your will.
Stepchildren: Close in Life, Invisible in Law
Stepchildren generally do not have automatic inheritance rights in Australia unless they’ve been legally adopted; superannuation does not automatically form part of deceased estates and is not controlled by the will. If your will says “to my children,” it may not include your stepchildren at all, even if you raised them, and that can affect both legally adopted children and your own biological children. Super can also be a significant asset and often includes life insurance policies.
The reverse also matters. A stepchild who was financially dependent on you, or who had a close relationship creating a moral obligation, may be eligible to bring a family provision claim against your estate. So ambiguity cuts both ways: unclear drafting can accidentally exclude a stepchild you wanted to provide for, or expose your estate to a claim you didn’t anticipate.
Either way, the answer is the same: be explicit. Name who is included, and where you’re deliberately leaving someone less, or nothing, consider documenting your reasons and making proper nominations so benefits reach the intended beneficiaries.
The Risk of a Family Provision Claim
Even a valid will can face a successful challenge. Spouses, children (including adult children), and certain dependants can bring a family provision claim arguing they were not left adequate provision. Blended families are among the most common battlegrounds. A biological child may argue the new spouse received too much; a stepchild may argue they were unfairly excluded.
Courts weigh competing moral duties, including each person’s financial circumstances, what each party has already received (including non-estate assets like super and jointly held property), and each person’s financial need. Well-structured planning doesn’t just direct your assets, it reduces the likelihood that they end up litigated, which itself preserves both wealth and relationships, with these disputes governed by the Succession Act in the relevant state or territory.
Choosing Your Executor Carefully
One underrated decision: who administers your estate. In a blended family, appointing your new spouse as sole executor when your children are beneficiaries, or vice versa, puts one side in charge of the other’s inheritance. Even where everyone acts honourably, it creates the perception of conflict and is a common flashpoint. An independent executor, or co-executors who bring both impartiality and family understanding to the administration of deceased estates, can defuse this before it starts and help preserve family harmony.
Have the Conversation
The most protective thing you can do is often not a document at all. Most blended family disputes are fuelled by surprise: children who assumed they’d inherit the family home, a spouse who assumed they’d keep it, nobody having said anything out loud, when open discussion among family members can reduce future conflict.
Discussing your intentions with your partner and children while you’re alive lets you explain your reasoning, manage expectations, and settle disagreements while you’re still there to mediate them, with the aim of helping everyone feel treated fairly. It’s uncomfortable. It’s far less painful than the alternative.
Regular reviews matter because circumstances change, especially in blended families.
How Money Path Can Help
Planning for blended families is where financial advice earns its keep, because the questions aren’t just legal. They’re about how much your spouse actually needs to live on, what your children can reasonably expect, how your super and insurance should be directed, and what’s fair given everything each person has already received.
At Money Path, we help you work through exactly that. We map your full financial position, including the assets that don’t pass under your will, such as superannuation, insurance and jointly owned property, which is where most blended family plans come unstuck. We model what your surviving partner would genuinely need for financial security, including shared cash flow and a joint budgeting approach for shared expenses, and what that leaves for your children, so decisions are made on numbers rather than assumptions. We help you understand which structures fit your situation, whether that’s a testamentary trust, a life interest, or tenants-in-common ownership, and the tax consequences of each, as part of a comprehensive estate plan that also accounts for minor children and the risk of financial mismanagement where inheritances are received too early. And we coordinate closely with your estate planning solicitor so the legal drafting, the super nominations and the financial strategy all say the same thing. In blended family estate planning, the plan should be reviewed every two years.
We also help with the harder part: thinking through what “fair” looks like for your family, using key strategies to balance the interests of a current partner, children from a previous relationship, and other family members.
Your legacy shouldn’t be a dispute. If you’re in a blended family and want to be confident everyone you love is protected, talk to the team at Money Path about a financial and estate planning review.
Frequently Asked Questions
Why do blended families need different estate planning? Because a standard will, leaving everything to your spouse and then to your children, creates competing interests when the children aren’t shared. Your surviving spouse could remarry, change their will, or spend the assets, leaving your biological children with nothing. Blended families need structures that provide for a partner while preserving capital for children from previous relationships.
What is the sideways inheritance trap? It’s when a parent leaves their entire estate to a new spouse, assuming that spouse will eventually pass it to the parent’s biological children. Instead, the surviving spouse may remarry (which usually revokes their will), change their will to favour their own children, or spend the assets. The family wealth moves “sideways” into a different bloodline, and the original children inherit nothing.
Do stepchildren automatically inherit in Australia? No. Stepchildren generally have no automatic inheritance rights unless they’ve been legally adopted or are specifically named in the will, and intestacy laws also do not automatically protect them unless some other legal status applies. A will that says “to my children” may not include stepchildren at all. However, a stepchild who was financially dependent on you may still be eligible to make a family provision claim against your estate, so clear drafting matters in both directions.
Does my superannuation go to my new spouse or my children? That depends on your binding death benefit nomination, not your will. Super isn’t automatically part of your estate; the fund’s trustee decides who receives it unless you’ve made a valid binding nomination. Without one, in a blended family this often means dispute and an unintended outcome. Note that many nominations lapse after three years and should be reviewed after any major life change.
How can I provide for my new partner and still protect my children’s inheritance? Several structures can do both. A testamentary trust can give your spouse income for life while preserving the capital for your children. For example, if you have two adult children from an earlier relationship, staged control can help support a new partner now without losing the children’s eventual inheritance. A life interest or right to reside lets your partner live in the family home, after which it passes to your children. Owning property as tenants in common, rather than joint tenants, means your share forms part of your estate and can be left to your children.
What’s the difference between joint tenants and tenants in common? It’s crucial in blended families. Property held as joint tenants passes automatically to the surviving owner on your death. It never enters your estate, so your will can’t direct it to your children. Property held as tenants in common means your share does form part of your estate and can be left to whoever you choose. Changing the ownership structure can determine whether your children inherit at all, and those choices can directly affect asset distribution.
Are mutual wills a good idea for blended families? They can be. Mutual wills are a binding agreement that neither partner will change their will after the first dies, protecting children from previous relationships. But they’re rigid, meaning the survivor can’t adapt to genuinely changed circumstances, and they can be difficult to enforce. Many advisers consider a testamentary trust the more flexible way to achieve a similar protection.
Can my will be challenged by my blended family? Yes. Spouses, children (including adult children), and certain dependants can bring a family provision claim arguing they weren’t adequately provided for, and blended families are among the most common contexts for these disputes. Courts consider competing moral duties, financial need, and what each party has already received. Clear, well-structured planning and documented reasoning reduce the risk.
Who should be the executor in a blended family? Choose carefully. Appointing your new spouse as sole executor when your children are beneficiaries, or vice versa, puts one side in charge of the other’s inheritance, creating real or perceived conflict. An independent executor, or co-executors representing both sides of the family, can significantly reduce the risk of disputes during administration.
What happens if there is no valid will? Your estate is usually distributed under intestacy laws, which follow a statutory order rather than your personal wishes. That can leave de facto partners, stepchildren, and biological children with outcomes that differ sharply from what you intended, especially in a blended family.
Who should I think about when naming beneficiaries in a blended family? Start by identifying everyone whose interests may need to be balanced, including former partners, your current partner, and children from different relationships. Being explicit about who you intend to benefit helps avoid confusion, perceived unfairness, and later disputes.
What should a life interest say about the family home? It should clearly spell out who pays for property maintenance, including rates, insurance, and general upkeep. That reduces the chance of later arguments between the person living in the home and the beneficiaries who inherit it later.
This article is general information only and does not take into account your personal objectives, financial situation or needs, and is not legal or tax advice. Wills, trusts and estate structures must be prepared by a qualified solicitor, and rules vary between states and territories. Always seek personal legal, tax and financial advice before acting.
