If you wish to split up your seats for sale, you should create separate listings and make a note within each listing that the adjacent seats are available in Listing # [InsertListingNumber].
If you want to list seats together and they already exist in separate listings, you'll need to delete the existing listings and create a new one with the seats together.
Seats listed together should always be in the same section, row, and adjacent seats. If seats cross sections, rows, or skip seats, they will need separate listings.