When Estate Planning Goes Wrong: Whittorn v Siu

You buy a home with your partner. You pay for it, but put it in both your names as joint tenants. The two of you agree that your partner can live there for life and that, after their death, the home will go to your children from an earlier relationship. Your will leaves everything to the children. Is that enough?

In Whittorn v Siu [2026] NSWSC 666, decided on 11 June 2026, the NSW Supreme Court considered an arrangement of this kind. The intended arrangement had not been formally documented. After the father died, his sons and his partner ended up in court, collectively spending more than $300,000 litigating over the property.

The sons succeeded on their property claim because the Court found an enforceable agreement. The case shows why the ownership of your home, your will and any promises about a future inheritance need to work together.

What you need to know

• Your will does not itself redirect property held as joint tenants. When one of two joint tenants dies, the surviving owner ordinarily retains the whole property by survivorship.

• Survivorship does not necessarily remove other obligations. Here, the Court found that the surviving partner had agreed to leave the apartment to the deceased’s sons under her will.

• The sons were to inherit through her will. The Court did not find that the apartment simply passed to them under their father’s will.

• An unwritten arrangement can be difficult and expensive to prove. This result depended on the evidence, including the surviving partner’s admissions in cross-examination.

• Plan and document the arrangement early. For blended families, making a will is only one part of the process.

  
  

Joint tenants and survivorship

When two people own property as joint tenants, neither has a separate share that they can leave under a will. Together they are entitled to the whole property. On the death of one joint tenant, the surviving joint tenant ordinarily remains entitled to the whole.

The judge explained this through the principle of the “right of accrual”. Death terminates the joint tenancy; it does not sever it into separate shares. Strictly speaking, the survivor does not inherit the deceased’s share under a will. The property is freed from the deceased owner’s rights.

That differs from ownership as tenants in common, where each owner has a distinct share that can ordinarily pass under their will.

However, survivorship does not necessarily release the surviving owner from a binding agreement or other equitable obligation affecting the property. That qualification was central to this case.

What happened in Whittorn v Siu

Mr Whittorn separated from his wife after about 40 years of marriage and later formed a relationship with Ms Siu. The Court found that their relationship had been a de facto relationship for approximately eight years before his death.

In 2019, Mr Whittorn contracted to buy an apartment in Tweed Heads, NSW. He funded the purchase entirely himself, but the contract recorded him and Ms Siu buying as joint tenants.

His emails to his conveyancer show him considering how to provide security for Ms Siu while preserving an inheritance for his sons. On the morning of 20 May 2019, he wrote that he saw “problems with joint ownership. Big problems”. He wanted Ms Siu to use the apartment if he died, but wanted it to go to his sons after her death.

That evening, he instructed the conveyancer to retain joint ownership, explaining that they could deal with what happened on death through their wills. The conveyancer explained that the surviving joint tenant would become the sole owner. Mr Whittorn confirmed that joint ownership was acceptable and that both of them needed wills covering the possible outcomes.

The purchase settled in January 2021. In August 2021:

• Mr Whittorn made a will leaving his whole estate to his two sons in equal shares.

• Ms Siu made a will leaving $50,000 to a friend and the residue to Mr Whittorn, or to his two sons in equal shares if he did not survive her.

Mr Whittorn had also contributed $430,000 to Ms Siu’s superannuation during his lifetime. He died on 20 March 2023. The apartment was subsequently registered in Ms Siu’s sole name following lodgement of a notice of death. On 28 April 2023, less than six weeks after his death, she made a new will leaving her estate to the Royal Brisbane and Women’s Hospital Foundation.

The sons lodged a caveat on 22 June 2023. On 2 August 2023, the Court extended the caveat until further order and restrained Ms Siu from transferring, charging or otherwise dealing with the apartment without the sons’ prior written consent or the Court’s permission.

Why the sons succeeded

A binding agreement qualified the joint ownership

Meek J found that the apartment had been placed in joint names under an agreement that Ms Siu could live there for the rest of her life and would leave it to Mr Whittorn’s sons under her will. The judge was satisfied that the agreement was intended to be legally binding.

Ms Siu’s admissions in cross-examination were particularly important. She acknowledged discussions before the apartment was acquired under which it would be put in both names and she would leave it to the sons. The Court also considered the contemporaneous emails and other witness evidence.

The judge was not persuaded that Mr Whittorn misunderstood the effect of joint tenancy. The central issue was whether Ms Siu’s ownership was subject to an enforceable agreement about the apartment’s ultimate destination.

The Court’s finding did not bring the apartment into Mr Whittorn’s estate to be distributed under his will. Ms Siu’s legal ownership was subject to the agreement, under which the sons were to receive the apartment through her will after her death.

Estoppel provided an alternative basis

If there was no binding agreement, the judge found that Ms Siu had made a clear promise on which Mr Whittorn relied when arranging joint ownership. Without that promise, he would have taken steps to secure the intended arrangement for his sons.

On that alternative basis, she could be restrained from dealing with the apartment contrary to the promise. The reasoning depended on the promise, the reliance it induced and the detriment that would follow if she departed from it.

The absence of a formal written contract did not defeat this claim

The case also raised the writing requirements in section 54A of the Conveyancing Act 1919 (NSW). That provision generally restricts enforcement of a contract for the sale or other disposition of land, or an interest in land, unless the agreement, or a sufficient written note of it, is signed by the person against whom it is being enforced or an authorised representative. The section preserves the law relating to part performance.

Here, the point had not been pleaded as a defence or argued at the hearing. The judge also questioned which statutory provision applied and identified equitable principles that prevented the absence of writing from defeating the sons’ claim on these facts.

The outcome is no substitute for properly documenting an estate plan. Proving an oral arrangement after someone has died can involve difficult questions about what was agreed, what each person did in reliance on it and which legal remedies are available.

A right of residence with limits

The judge considered that Ms Siu’s entitlement was best characterised as a lifetime right of residence rather than a life estate. There was no evidence that the arrangement contemplated her moving out, renting the apartment to someone else and keeping the rental income.

On the Court’s findings, the agreement also did not permit her to sell the apartment and use the proceeds to buy replacement accommodation. The sons, meanwhile, might have to wait many years before receiving the property under her will.

These distinctions matter when preparing an estate plan. The documents should address whether a surviving partner can move, rent out the home or buy a replacement property, as well as responsibility for rates, insurance and maintenance. Those details should be discussed while everyone can explain and record what they intend.

The relief discussed in the judgment

In the reasons delivered on 11 June 2026, the Court found in the sons’ favour on the property claim, but left the formal orders to be settled. It directed the parties to bring in proposed orders giving effect to the reasons and reserved costs.

The judge indicated that appropriate relief would include a declaration recording the agreement and an injunction restraining Ms Siu from acting contrary to it. He also explained that an injunction could be recorded on the property’s title through NSW Land Registry Services.

Ms Siu and one of the sons, Christopher, had also brought family provision claims. The judge was not satisfied on the evidence that Ms Siu had been left with inadequate provision. He considered Christopher’s alternative claim in case the property findings were wrong, but said further information would be needed before making any provision. As matters stood, he would make no family provision order.

Costs were a serious concern. The judge warned that if Ms Siu were required to pay the sons’ costs, the value associated with her right of residence might need to be realised to meet that liability, potentially jeopardising her ability to remain in the apartment. That was a possible consequence identified in the reasons; the question of costs was reserved.

Practical lessons for blended families

1. Check how your home is owned

A will does not itself redirect property held as joint tenants. Check the title and obtain advice about how the ownership structure affects the outcome you want for your partner and children.

2. Make the ownership and estate plan work together

Providing a home for a surviving partner while preserving an eventual inheritance for children requires coordinated planning. The ownership structure, wills and any binding agreement need to give effect to the same plan.

3. Record the arrangement properly

Be clear about what the surviving partner can do with the property, when the children’s entitlement arises and what happens if circumstances change.

In this case, contemporaneous emails, witness evidence and Ms Siu’s own admissions helped establish the arrangement. Other families may struggle to prove what was agreed.

4. Do not assume that matching intentions make wills binding

Wills that reflect a shared plan do not, by themselves, establish an agreement that the plan cannot be changed. A will is generally revocable, although a separate binding obligation may be enforceable even if a later will is made.

Obtain advice about the wills and any agreement needed to support them. Our article on mirror wills for couples explains more.

5. Obtain advice promptly if a dispute arises

If you believe you have a claim to property, a lawyer can assess whether you have an interest capable of supporting a caveat and whether urgent court protection is needed. Being named in a will does not automatically give you a right to lodge a caveat over every property associated with the deceased.

If you are the surviving owner, seek advice before selling the property or changing arrangements that may be subject to an agreement. Having the property registered in your name may not end your obligations.

6. Consider the cost of a dispute

The judge observed that the parties were not far apart in some respects about what should happen to the apartment. The sons wanted Ms Siu to be able to remain there, with the property ultimately going to them. Even so, the parties collectively spent more than $300,000 litigating.

Early advice and, where possible, a negotiated resolution can help avoid the financial and personal toll of a prolonged dispute.

For related information, see Protecting Your Estate from Family Provision Claims and our Family Provision Claims overview. Time limits apply to family provision claims, so obtain advice promptly.

How Surge Legal can help

Our lawyers help blended families plan ahead. We can review how your home is owned, prepare wills that reflect your intentions and advise on disputes after a death, including claims affecting property. Find out more about our wills and estates and property law services.

Appointments in English, Mandarin and Russian can be arranged at our Parramatta office. Saturday appointments are available from 10am to 1pm by prior arrangement.

A free initial 20-minute consultation is available by appointment for general wills and estate enquiries. Detailed estate-dispute advice requires a paid consultation, with the fee explained before booking.

Call (02) 8551 7851, email info@surgelegal.com.au or book an appointment online.

This article provides general information about the reasons delivered in Whittorn v Siu [2026] NSWSC 666 on 11 June 2026. In those reasons, the Court directed the parties to prepare proposed orders and reserved costs. It does not constitute legal advice. Every case turns on its own facts. Please contact Surge Legal to discuss your circumstances.