Borrowing money for stamp duty

[Alli]

We were going to borrow the monies required for stamp duty, until we sell our house, which is currently rented. However, parents have offered to lend the amount, and we will pay them back an agreed set rate until we sell the property. This seems like a great opportunity for us as involves no interest.

However, do we declare this as a regular loan when applying for mortgage with the bank.

Are there implications on this kind of lending?

thanks,

Alli