Sounds like your best bet would be just make cuts from the middle of each stud and as tall a piece as you want to deal with. If you want to replace a whole sheet you can do that also, your choice I suppose. I know a guy that does it but wouldn't recommend him unless you weren't in a big hurry. Of course working for someone other than us he might move a little faster on the job. He does do good work and if it's nothing big I'm sure he wouldn't take too long if he has the time. If you want I can get his number and PM it to you.