Question: Gifted Deposit, Increased Amount

Fonque

I am a FTb and have had an offer accepted on a flat.

My MB has sent off the application form and has sent me the Key Facts illustration, outlining the interest rates etc and a form for a Gifted Deposit, as some of the deposit was generously donated by my mother.

My mother reviewed her finances and says she could spare a little more for the deposit.

Since the application has been sent off is it too late to amend the amount of money my mother is gifting towards the deposit (since it will impact the amount of money I will be borrowing and therefore the Key Facts will then be incorrect)?

Or should I just keep it to one side then overpay (up to my overpay limit) with it instead?