Doubt that would work. SC's are usually assigned in the afternoon the day before. Some shifts start as early as 3 or 4 AM, necessitating putting the pilot into rest at least 10 hours prior so they're legal for the SC period. There's also the variables of how many days each pilot has available. Tring to throw in some sort of swap system on top of all that doesn't seem feasible. As someone else said if your volunteering for SC just put in the restrictions you want and you'll either get what you want, not get SC, or if you were due for SC anyways scheduling will still give it to you, just maybe outside the parameters you wanted.