How to Prevent Sideways Disinheritance in Blended Families

When making a Will, it’s vital to ensure your intended beneficiaries — such as your children — actually receive what you want them to. This becomes especially important in blended family situations, where remarriage or changing relationships can put inheritances at risk.

Without careful planning, assets can unintentionally “move sideways” into the hands of unintended individuals, such as a new partner, instead of the children or family members you originally wished to benefit. This is known as sideways disinheritance.

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What is sideways disinheritance?

Sideways disinheritance occurs when beneficiaries — often children — are unintentionally excluded from an inheritance. This typically happens if a surviving spouse remarries or alters their Will. It is especially common when couples make mirror Wills (two nearly identical Wills leaving everything to each other, and then to the children).

In England and Wales, marriage itself revokes a Will unless it is explicitly written in contemplation of marriage. This means that remarriage, divorce, or failure to update a Will can dramatically alter how assets are passed on under intestacy rules.

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How sideways disinheritance happens

There are several common scenarios:

• Marriage revokes Wills – If you remarry without updating your Will, your existing Will is automatically cancelled. Unless you create a new Will, your estate will follow intestacy laws, which may exclude your original beneficiaries.
• Outdated mirror Wills – Couples who make mirror Wills often leave everything to each other, then to their children. If one remarries, however, the surviving partner may change their Will or intestacy rules may apply, leaving children from a previous relationship with nothing.

Example scenario:
John and Anna make mirror Wills leaving everything to each other and then to their children. After their divorce, John remarries but does not update his Will. When John dies, intestacy rules result in assets passing entirely to his new spouse, unintentionally disinheriting his children from his first marriage.

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Why it matters

Losing control over how assets are distributed can cause long-lasting emotional and financial strain on families. Without the right protections, your legacy may end up benefiting someone you never intended — while those you care about most are left with nothing.

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How to avoid sideways disinheritance

✅ Review and update your Will regularly
Update your Will after major life events such as marriage, divorce, remarriage, or the birth of children.

✅ Name all children clearly
Be explicit in naming all children, including those from previous relationships, to ensure clarity and inclusion.

✅ Use protective trusts (e.g. life interest trusts)
Trusts can safeguard assets for your children. For example, a life interest trust allows your surviving spouse to benefit during their lifetime, while guaranteeing that the assets ultimately pass to your chosen beneficiaries.

✅ Discuss your plans with loved ones
Open and honest conversations reduce the risk of misinterpretation or disputes later.

✅ Seek tailored legal advice
Blended families require bespoke estate planning. A professionally drafted Will or trust ensures your wishes are protected even if your circumstances change.

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Final Thoughts

Sideways disinheritance is a real risk in today’s modern families, but it can be avoided with careful estate planning. Regularly updating your Will, using trust structures, and seeking professional advice are the best ways to ensure that your estate is passed on exactly as you intend.

At Viva Planning, we provide expert guidance on Wills and trusts, helping families safeguard their legacies with confidence and care.