I've had that problem with relatives before. And I've gotten downright rude about it too. I actually kicked an uncle out of my house because he couldn't behave around my puppy. And with most other family, if they don't listen the first time, I've taken to crating Kaiju with a yummy Kong during their visit. When they ask why he isn't out, I tell them I'll let them meet him when they earn that privilege by following my greeting rules. Some have come around. Some don't get to see him.
It's really no trouble to me if he just doesn't meet some members of my family. If they won't behave around him, I just won't put him in that situation. I'll wait until his manners are bomb-proof and THEN he can meet the less respectful family members.