Accommodation advice - living with parents

[Confusedmum]

Hi, this is my first post on the forum, I’ve looked elsewhere for an answer but can’t seem to find a definitive one.

My daughter and her fiancé are currently applying for a fiancé visa. They plan to live with me if he is successful until they have the funds to move into their own home but there is no rush for them to move. Our house is mortgaged (myself and husband). It is a large 4 bedroom Victorian semi with 2 large reception rooms in addition to the double bedrooms and Spam-diner/bathrooms/utility room. It will be occupied by myself and my husband, my adult son and daughter and her fiancé so they will have a bedroom and the spare bedroom will be their ‘living room’.

We are more than happy to provide all of the necessary documents for her to submit for the visa but her immigration specialist has said that we need to get a property survey done and there-in lies the problem as we are at the beginning of a complete renovation of the ground floor so I’m not sure (in fact very doubtful) that it would pass an inspection in its current condition which means that they will either have to wait for around 18 months to 2 years for it to be completed or look for alternative accommodation which will obviously cost them a lot more money.

I have read conflicting advice and wondered what the rules were, do we need a property inspection carrying out seeing as they are going to be living with family?

Many thanks