Life interest Will invalid - DOV/deprivation?

We have a client whose wife has passed away. They did wills by post with some sort of guild. The tenancy was severed but their wills leaving their spouse a life interest in their half of property were not executed correctly and so are not valid.

Dad wants to do a deed of variation to put his wife’s half of the property in trust as they intended. However, I am concerned that this may be considered deprivation of assets as he is very elderly. His only son is named in the invalid wills as the ultimate beneficiary. However, his son is disabled, as is his wife and relies on benefits, lives in adapted social housing etc. If he were to take his mum’s half of the property outright he may lose his benefits. Likewise, if on his dad’s death, he were to inherit the whole house and residue he will lose his benefits and potentially his home. Dad’s house is not suitable for them to live in.

I would appreciate other opinions on whether a DOV would be appropriate here ( I appreciate I may be being overly cautious) or whether other options may be more beneficial.Thanks!

Kirsty Cartwright
St Helens Law