The way it will work is you will set the member’s preference at the membership level, and then, for members who do opt in, IF the member specifically wants to exclude one of his sub-accounts (like, say, a special checking account he uses for his church club or something), then you can set that as an exception. 

The idea with how we’re doing this is to make it easy to sell the member on “opting in for your overdraft services” then only handle sub-account exceptions on an as-needed basis for certain situations.