Not sure I understand your reservation, but it sounds like you have 2: one EA and one for a minivan (ER). I don't know if you'll be able to get a good rate from National for a minivan, and in my experience using the product codes only makes the price increase; I stick to corporate ID and coupon codes. If you really need a minivan, try Dollar with the code bb45. My sis rented for a week in June, $194 before taxes, etc. Hold your EA ressie, though. I got lucky in Dec and snagged a brand new minivan from EA, for $108 including all taxes, etc. Used priceless vacations code from mousesavers and a coupon for $20 off a weekly rental from BJ's. Right now I have a ressie for June (6/15-6/22) on EA for $104, all incl, using priceless code and BJ's coupon. I'm hoping for a PT cruiser (DD's alltime favorite) or a minivan...we'll see.
FYI, on the BJ's coupon...store associate says you do not have to be a BJ's member, just shop in their store. They stock the flyers with the coupons in a rack at the front of the store, for all shoppers to use. The flyer comes with the coupons and a BJ's travel services card. Works for me!