At least in the past, there are East Coast and West Coast CORTRAMIDs that are not on the same schedule. Recommend confirming those approx. timeframes for next Summer's activities, and requesting if you can attend the one that would not interfere with your sibling's graduation. I would check with your chain of command about exploring whether this request can be accommodated. Good luck/ hope this helps and congrats to your sibling on their college graduation.