Purely a legal question, but consider what you do when a customer claims that they didn't authorize you to make a transfer, or you charge a fee for the service the customer claims they never asked for.
I'm not an attorney, nor do I play one on the internet, but I'm going to say that you want some way of documenting that your customer authorized the sweep arrangement.
_________________________
Sola Gratia, Sola Fides, Sola Scriptura, Solus Christus, Soli Deo Gloria!
www.tcaregs.com