Don't worry about a having a specific game plan. Most game plans fall apart within the first few minutes of the first engagement anyway.
Without seeing the place I'd just suggest getting somewhere between the roost and where you think their heading. I'd set-up separate from your partner but maintain a visual, 60 yards or so if possible. That should give the two of you a better chance of someone being in the right spot. Both should do some calling but someone may wind up being the primary based on how the birds are moving, you'll just have to react to whats unfolding. Don't be afraid to get up and re-position, just make sure the two of you keep visual contact. If the birds get close I'd suggest the person the furthest away from the birds do the calling, more scratching than calling might be a good way to go. If your first set-up doesn't work get up move on them. When moving to another spot don't worry to much about being super quiet, the right kind of noise can be a good thing.