Make Pricing Agreement Apply Before Price List

Hi - I'll start by admitting I'm not normally supporting OM so this is what I hope is a very basic question.  I searched for the answer on Metalink, in the OM & Advanced Pricing implementation guides and this community and didn't find the answer, so I hope I've done my homework before bothering people with such a basic question.

We have a customer with a customer price agreement.  However, not every item is on the customer agreement but every item IS on our corporate price list.

In OM, at the header level, we have both a price list ("XXX") indicated and the agreement indicated ("YYY").  Item "ZZZ" is on both.