mortgage deposit confusion

Hi, im wondering if anyone can give their opinion on my situation.

My partner needs to sell his house to release equity (cant remortgage) and I have offered to buy the house in order for this to happen. I have have an offer in principle of 93k for a BTL mortgage. The house is valued at 130k.

93k allows mortgage to be paid off and equity released from the sale.

What we have now been told is that in order for the mortgage to be agreed we would have to physically show a deposit of 37k...

We believed that someone could sell their house for whatever price they wanted as the mortgage is offered on the valuation price? We were prepared to show a small deposit of the difference between the mortgage and the 'purchase price' tha we decide, if need be...but we dont have 37k! If we did he wouldnt need to sell the house!

Lawyer (convayancing) seemed to think that the deposit could be 'gifted' between the two of us but broker said that lenders only now allow this between family members or married couples...?

Anyone any experience of this type of situation?

We and the property in question are in Scotland.

Sorry this is in buying houses section of the forum as well.

Thanks.