How to get someone uninvited invited!! BUt....?

Okay, My friend Timmy is throwing a party for our other friend Henry. I've been liking this guy, Sam, for a bit but i haven't told anyone AND I DON'T PLAN TO! Henry's friendly with him espessially since the people invited to the party are good friends with Sam. But Timmy didn't invite Sam and I don't know if he forgot to or thought henry wasn't good friends with him or what! Anyway how can i get Sam invited w/o being obvious of my crush. (SAM NOR TIMMY KNOW ABOUT THIS! AND NEITHER DOES HENRY SINCE IT'S HIS SURPRISE PARTY)