Buying a property with annexe/outbuilding with planning permission with wife and in laws

[Jm4910]

Hi there,

My father and mother in law are looking to dwnsize to release money for retirement and my wife and I are looking to get a bigger property. We are looking at pooling our funds together to buy a house (for my wife and I) with a large annexe or an outbuilding that has planning to convert for residential use for (for the in laws).

My father in law would sell his house at £400k and put up to £300k towards the new property, and I would sell my house and put in £100k. Any extra borrowing which is likely would be through a mortgage either a joint one between just my wife and I, or if necessary with my father in law.

My wife has a brother too so we need to think about how he would get his share of the inheritance without selling our house.

Could somebody try and explain what pitfalls we might encounter with this arrangement and possible solutions?

Thanks

Jon