Unequal Inheritance Between Siblings: What Executors Should Know

Unequal inheritance between siblings can spark lasting resentment, confusion, and even legal action. Whether one child receives significantly more, or is left out entirely—these disputes often arise in blended families, second marriages, or when a parent changes their Will late in life.

Did a parent leave you less than your siblings, or nothing at all? If so, you may be wondering whether UK law allows you to challenge a Will, and under what circumstances.

This guide explains when adult children can contest a Will, how claims under the Inheritance Act 1975 work, and what steps executors should take when faced with disputes between siblings.

Example Scenarios of an Unequal Inheritance Between Siblings

Can an Adult Child Challenge the Will?

Yes—but only under certain conditions. Challenging a Will typically requires legal “standing” (e.g. being a beneficiary in a previous Will or under intestacy) and a valid legal reason. Grounds include:

• The Will wasn’t signed or witnessed properly
• The person lacked mental capacity when making the Will
• They didn’t fully understand or approve its contents
• The Will was made under undue influence
• There was fraud, forgery, or deception (e.g. fraudulent calumny)

Example Scenarios

In 2012, Sarah wrote a Will dividing her estate equally between her children. Diagnosed with dementia in 2014, she later made a new Will in 2016, heavily favouring one child. When she died, the other children were shocked. They challenged the Will, arguing lack of capacity and undue influence.

These claims can succeed—but they must be supported by evidence, such as medical records or solicitor files.

What About a Claim for Financial Provision?

Even if the Will is valid, adult children can make a claim under the Inheritance (Provision for Family and Dependants) Act 1975 if they believe the Will fails to provide “reasonable financial provision.”

To succeed, adult children generally must show:

• They were financially dependent on the deceased, or
• They have a genuine financial need

Example Scenario

James receives only £5,000 in his mother’s Will. He has a disability and struggles financially. During her lifetime, his mother regularly supported him. His stepbrother, Frank, inherited most of the estate and is financially stable.

James makes a claim under the 1975 Act, arguing the Will didn’t provide enough to meet his needs. The court can order an adjustment to the distribution if it agrees.

Are There Other Options?

Yes depending on the facts, other routes may include:

• Challenging lifetime gifts made under undue influence
• Disputes over jointly owned assets
• Claims of proprietary estoppel (promises made and relied on)

Each case is unique, and adult children are advised to seek legal support early to assess their options.

Disputes over unequal inheritance between siblings can be emotionally charged and legally complex. Whether you’re an executor facing complaints or an adult child considering a claim, it’s essential to understand your position and seek professional advice early.

The right guidance can help resolve issues fairly and avoid drawn-out legal battles.

Disclaimer: This article provides general information only and should not be taken as legal advice. For personalised support, please consult a qualified probate solicitor.

Don’t Overlook the Risk of a Contentious Probate Claim, or Miss the Warning Signs

As an executor or administrator, you can be personally liable for defending claims and covering losses if you don’t have Probate Insurance, even when the claim is made against the estate, not directly against you.

Contentious probate isn’t limited to courtroom battles; it often begins with disagreements over who inherits, how the estate is handled, or whether the Will is valid.

These situations may involve someone being left out of the Will, a dispute over how much someone should receive, concerns about how the Will was created, or confusion when no Will exists. Claims under the Inheritance (Provision for Family and Dependants) Act 1975 are particularly common.

Such disputes can delay the probate process, increase costs, and expose executors to personal liability. It’s far better to identify and address potential risks early, before they escalate.

Arrange a FREE consultation with a Contentious Probate Solicitor.
They’ll assess your situation, confirm whether a claim is unlikely (which may help you qualify for Early Distribution Insurance), or provide expert guidance on how to protect both yourself and the estate.

Book Your Free Consultation

Content Note: This page is based on original materials provided by IDR Law, with thanks for their permission and collaboration.