It specifically states that annual pass holders do not get free admission. That is why there isn't a section to make a reservation. They would need to buy a ticket to come to the park. From the FAQ:I was able to make reservations using our legacy pass barcodes and preschool pass by clicking the button labeled " Preschool Pass, Military Pass and previously purchased Busch Gardens Williamsburg 1-Day Tickets make reservations here. " There is nothing on the page indicating where legacy passholders should make reservations. That seems like perhaps preschool passed are accepted but legacy passes are not. However, my reservations went through with no problem the combination of barcodes. This is very confusing. The park need to specifically put in writing on the reservations page which section legacy passholders can reserve in and whether or not we need to purchase tickets.
I do want to point out that this isn't new. Legacy annual passes have never been given admission to these events.
It will allow you to make a reservation, because the system isn't checking if your barcode is valid for the event. It's really mostly just saving it so that when you scan your reservation it can match to the barcode you provided.