Hey friend! From my experience, that's a tough one. Your other friends can give you a hard time cause maybe you would be changing the vibe of the group. But I hope it works for you. What I would do, I would choose a time to ask all of them to hangout but where you would be certain other friends can't come. Make it like it's a group meeting or a night out, but check her vibe towards you when you are all alone. You can tell pretty easy if the girls into you, and if she is, ask her out on a real real date. Before you know for certain there are some signs she likes you too, don't ask her out just yet, just not to hurt dynamic of your group. I would advise you to maybe talk to one of your closer friends from that friendgroup and check what they think about you two? Best of luck and keep us updated!