2 girls I know coming over at the same time, both want to sleep in my bed with me

my flat that I share with a bunch of students (including me) are having a party on monday and we'll also be going to a big student event.

My flatmates are bringing over their friends and I invited a girl call her girl A that i've been seeing on and off, I know she is really into me and this is my chance to hang out with her properly and most likely be going off with her.

I have a female friend Girl B who I was good friends with last year but has gone back to live in her hometown now shes finished uni, she asked if she come up and I said sure why not as I haven't seen her since new years eve.

There is a problem, I want to hang out with both of them but want alone time with girl A if you get what I mean but I don't want to ditch girl B who doesn't know anyone part from me and she wants to stay in my room. My other flatmate's rooms are full as well and a group of lads friends will be sleeping on the sofas in the living area.

what do I do? I don't want to be a dick or leave out any of them.