I'm returning from my wedding in UC, my witness will be in economy on the same flight. Can I invite him and his wife into the bar for a sneaky wee drink?
Normally that would be a no as the bar is for UC passengers. Having said that, try having a word with the FSM to see if they are amenable to that.
Nothing wrong with asking but expect a no and best to leave it until the meal service has finished too. You might be surprised.