I have a serious question about this first. How many people are in the group, and, does everyone in the group have their own room, or would you have to share with someone in the group?
Here's what I'm thinking. If your friend comes and the group sees that, there's gonna be questions about why is another person in the room with you.
I think if you ask the group guide, it's probably going to be no. That's like, if I had a friend living in Annapolis MD., and we went on a field trip and I asked my friend to meet up, it wouldn't work because I can't just go off where I want, and if this random person shows up, the chaperones are gonna say, who is this person? They shouldn't be here etc. etc. and I'd get in trouble.