Social Circle Penetration number close

I'm looking to pick up a HB9 within my social circle. We've met a few times because recently she's been in my apartment complex chilling with my floormates. She's constantly giving me IOIs like repeating my name (when at first I didn't know her's), whining to her friends when I'm going out and her friends want to stay in, and laughing at even my cheesiest jokes. The first thing is she's a little shy, the second thing is, as I mentioned she doesn't go out much and she's always with her friends. I've had opportunities to Number Close but her friends have been around and would have made her uncomfortable. Does anyone have a foolproof plan or routine to give me an excuse to number close? Any recommendations to get her quiet friends out with my group, or even extract her from her group with out making my floormates feel rejected?