I think the best way to handle this is to have a comma delimited list of sheets that are closed.
So if you wanted 3,4,5,6 you would specify that "1,2" are closed. If you wanted to use sheets 1,2,4,5, then you would specify that "3" is closed. etc.
This will also allow you the flexibility to exclude the edges in a competitive league for example. E.g. "1,8" to use only 2,3,4,5,6,7 (or B,C,D,E,F,G).