I'm not sure if you're able to do it in advance of your arrival to the clubhouse, but you can certainly give your guests details if you've already arrived and they're arriving later.
I was travelling UC and my parents were in PE, as I could only take 1 in as a guest, a friend who was also travelling UC offered to take the other in. I arrived with my parents in the clubhouse (Gatwick) prior to my friends arrival, I asked if it was possible both my parents could come in with me at that time as my friend was going to take the other in as his guest when he arrived, I was asked to verify my friend's name, flight details and if he was travelling with anyone else - it was no problem at all doing it that way but not sure if it would have worked had they been travelling by themselves and both myself and my friend were arriving after them.