How this worked last year (and I hope it will work again this year)
I get a number of tickets we are likely to use and give that to the Bills along with where we want the tickets to be (we were in 338 last year)
The Bills reserve that many tickets for us and give us a special link and password for people to use
I send the link and password to people who signed up so they can purchase their tickets from the block via ticketmaster. This way all money and delivery is handled by them, and all seats are guaranteed to be together.
Once tickets in the block are gone, we're done. If some go unsold the ticket office reclaims them on a given date