If we disclose on line the fee for monthly bill pay do we need to include this fee in our disclosures for Reg DD when opening a new account at a branch?

Do you have to? No. Bill pay is not an integral feature of any account, since customers apply for this service à la carte.

Should you? Your call.

What you do have to do is make certain each of your customers applying for bill pay service gets the disclosure of your fee. It's a Regulation E disclosure.

I wouldn't simply because this is an elective product that a minority of customers will use. You could also open yourself up to change in terms notices later to the universe of customers instead of the users, or at best needless disclosure modifications.

You'll disclose this cost prior to enrollment into the product anyway, so it will be covered more timely and with an interested audience.