My parents made DIY will changes but lawyers say it isn't valid - how do I avoid a family squabble over their inheritance?

My parents made mutual wills in 2006 and named each other as their executor. I was set to receive a 50 per cent share in their home after the first parent died, with the remaining assets being passed to the survivor.

Their wills state that upon the death of the survivor, the assets were to be split between their grandson who gets 50 per cent, myself with 25 per cent, and the remaining 25 per cent to be split between step-granddaughter (A) and a niece, who would get 12.5 per cent each.

A further step-granddaughter (B) was excluded from the will as she was estranged from my parents and had moved to New Zealand.

However, the estranged step-granddaughter (B) later came back into the family fold. My parents both wanted her to receive a share of the remaining survivor's assets.

A homemade codicil was drafted stating that the 25 per cent share that was originally gifted to step-granddaughter (A) and their niece was now to be split three ways with step-granddaughter (B), giving them 8.33 per cent each.

The codicils were signed and dated by both parents and one independent witness. They were both of sound mind at the time of signing.

Inheritance dilemma: My parents were of sound mind when they made a codicil to their wills - can it be honoured? (Stock image)

My father died in 2021 and my mother now lives in a care home as she has Alzheimer's. Their home has been sold and I received the 50 per cent share.

However, during this process I was told the codicil is 'not worth the paper that it's written on' because my parents made mutual wills and these cannot be changed.

I know I will find myself in the middle of a big family squabble if, when my mother dies, there are any assets left to divide.

Will the codicil really be invalid? Your advice would be much appreciated.

Tanya Jefferies, of This is Money, replies: You are clearly trying to do the right thing by your parents and the rest of your family, but now appear to be stuck in a no-win situation.

A codicil is a legal document which amends part of an existing will, without the need to replace the entire thing. 

We consulted a solicitor experienced in this area of the law, who like your previous adviser says the codicil your parents made to their wills is worthless.

Nevertheless, she suggests a couple of ways for you to honour your parents' wishes which you could consider after your mother's death.

She also makes a compelling case not only against homemade wills and codicils, but against making mutual wills.

This should be of wider interest to This is Money readers who are making inheritance plans and have time to get them right.

Sarah Nettleship: Mutual wills are rare beasts that promise certainty, but whose rigidity can cause unforeseen problems

Sarah Nettleship, a partner specialising in estate tax and succession at Thomson Snell & Passmore, replies: The topic of mutual wills is one that makes most private client solicitors shudder, as they can be both rigid and uncertain at the same time.

Most solicitors dissuade their clients from using mutual wills and suggest alternative ways of protecting their estates.

However, in this case, the issue of mutual wills is not relevant as unfortunately the codicils your parents made were not signed correctly and are simply invalid. 

Codicils are subject to the same signing requirements as wills which means they must generally be signed by the person making the will or codicil, known as the testator, in front of two independent witnesses who also sign the will or codicil in the testator's presence. 

As the codicils were only witnessed by one person they are unfortunately invalid. 

This means neither of your parents successfully changed the terms of their original wills. Your mother's estate will pass in accordance with her original will when she dies, as she cannot change her will now due to it being a mutual will and her lack of capacity. 

It is always important to take specialist advice when dealing with wills and codicils as basic legal formalities can be easily overlooked, resulting in the homemade documents being ineffective.

After your mother's death, if you want to honour your parents' wishes, you could ask the beneficiaries of your mother's estate if they are open to the idea of varying their inheritance to follow the terms of the codicil.

However, they are under no obligation to do so and they would need to be happy for their entitlement to be reduced in order to benefit step-granddaughter B.

If they were unwilling to vary their inheritance, you could consider giving a portion of your inheritance to step-granddaughter B as this does not need the agreement of any other beneficiary. 

Any redirection of an inheritance to another person is a gift, but if you (or any other beneficiary) make this gift within two years of your mother's death using a deed of variation then there is no need to survive the gift by seven years for it to be tax efficient.

Why do solicitors dislike mutual wills? 

It is important to address why most private client solicitors do not recommend mutual wills. Under the law of England and Wales, people are free to leave their estates to whomever they please and there is a general dislike of any restrictions to this core principle.

Mutual wills are in effect a contractual agreement between two testators which prevents the survivor of them from changing their will after the first death. 

On the first testator's death, the property of the surviving testator is held on an implied trust for the beneficiaries of the mutual wills which means the second testator is no longer free to change how they leave their estate. 

This makes them very rigid and does not allow for changes which may be necessary following the first death. It is also sometimes unclear which assets are covered by the implied trust and what can be done with those assets during the survivor's lifetime. 

Even if your mother still had the capacity to put a new will in place reflecting the shared wishes of her and her husband, she is unable to do so as the mutual wills became binding on your father's death.

Mutual wills may be revoked or changed while both testators are alive and in agreement. 

During their lives, your mother and father were free to change their wills as long as they both agreed to any changes which means the codicils would have been effective if signed correctly.

If your mother did still have capacity, I would consider whether your parents' wills really were mutual wills. 

Mutual wills are very uncommon and can be confused with simple mirror wills under which a couple leave their estates to each other and then to the same beneficiaries on the second death. 

Mirror wills can be changed at any time so if the wills were mirror wills and your mother had capacity, she could change her will to bring it in line with the codicil.

Instead of mutual wills, in cases where married couples wish to ensure certain beneficiaries benefit from their estates after the second death, they should consider the use of a life interest trust in their wills instead. 

A life interest trust allows the assets of the first to die to be enjoyed by the surviving spouse during their lifetime but does not allow those assets to be disposed of by the survivor which preserves the estate of the first to die for their intended beneficiaries. 

The survivor is still free to change their own will, but this only covers their estate while the estate of the first to die remains protected in the trust. This makes these trusts a less rigid option and the trustees are often given flexible powers to enable them to react to changing circumstances as well.

This is a cautionary tale about homemade wills and codicils and the risk of not taking specialist advice on important legal matters.

It does, however, shine a light on the matter of mutual wills themselves; rare beasts that promise certainty but whose rigidity can cause unforeseen problems, as highlighted in this case.