Advice on Santander (A&L) Loan

Al2008

I have today recieved a credit agreement and direct debit form for a loan which I have taken out for my son as he is unable to get one. From the paperwork it is ok that it is going to be paid into his account as this is stated on the front letter. It is only a single application and I have signed the credit agreement. However, the direct debit is required to come out of his account and this is what I have put on the dd form. However, on this it states first customer signature and 2nd (if applicable). He has completed it with his bank details and signed it and I have signed the credit agreement, as he is not on the loan will it being his bank details and signature on the dd form cause any problems, or can you generally get a loan repaid from any account (in this case a Halifax).

Thanks in advance for any replies.