I did the same thing. The ticket office told me to line out the items that were already printed. For instance, I wanted 3 tickets instead of the 2 that I purchase the year before. Then, I was told to write in the box to the left (or somewhere on the invoice) what I desired for my new ticket arrangement. I did that and sent in my money. After it is processed, you can log in to My Dog Tag and see your ticket purchase. If all goes right, it will also say that the Bulldog Club should reference the invoice to check your seating request. You may have to look under My Seating Requests to actually see this comment.
Your original ticket purchase will still show the same seats you had last year at this time. And if you ordered any additional tickets, they will probably pop up in the General Admission section. Hopefully, all of this will be straightened out by the Bulldog Club after the June 1st deadline.
Hopefully, I have answered your questions.