Once again - you don't need to explain yourself. Personally, I'm very rarely ever asked who I'm with unless I ask first.
Should it come up, however, just say that your friends are in there somewhere, that you split up when you had to piss. You could even ask her to help you find them, and walk arm in arm or hand in hand around the club looking for them - of course you won't find them, but not only is this a good tester(is she willing to go off alone with you? Will she take your arm/hand?), it also is a good point of kino escalation AND builds social proof to the others
So, to sum it up, if they ask who you're with:
-When you're in A1(just met them, ran an opener): This is kinda an IOD at this stage(kinda like saying 'Shouldn't you be with YOU'RE friends instead of us?'), meaning you kinda sketched them out. Nothing you can really do here besides say 'my friends are here somewhere'
-When you're in A2(starting some DHV routines, negging the target): Say 'there here somewhere, won't you guys help me look for them?' Offer your hands/arms. Won't work on a set more then 3, works best with a 2 set. EXCELLENT DHV and social proofing if you wanna open more sets later.
-When you're in A3/C1(Qualification stage): PERFECT time to isolate the target. Grab her hand and walk away. Does she give you her hand willingly? If you lighten your grip, does she let her hand fall away, or do your fingers stay loosely interlocked? Can you interweave your fingers with hers? If yes to any of them, you are doing good, if yes to all, VERY good. Once you have her away, start comfort building, go for a kiss - if you get the kiss, make sure YOU end it and say 'hey, thats it for now, lets get back to our(NOTE: HER) friends'.
Good luck.