Originally Posted by
dilangc 
I think what we're struggling with is hoping (probably naively) he can get it together for a long weekend. Long enough to enjoy this special day
There are no guarantees with recovery.
What is your Plan B if he doesn't get his act together before the graduation? Un-invite him? Make him blow a breatherlizer?
If he is active again in his addiction (and he agrees not to drink for that one weekend), he will likely be a snappy, moody, lack-luster person who can't wait for the end of the weekend so he can go have a drink. His next drink will be his focus.