Mortgage direct debit payment

Worried

Is it possible to change the account from which your mortgage repayments are made? OH and I have applied for mortgage, but hadn't sorted out opening a joint account yet, so filled out the DD form so the payment will come from my current account. I would prefer that this came from a separate account which would both pay into, so I can keep better track of my money. Is it easy enough to change the account from which the mortgage is paid? Can we do this before the mortgage starts, or once we've started repayments. Anyone know if they would charge a fee for this? Mortgage is with Abbey.