Besides finding a new target 
?
Oh to be 17 again…
Seriously, I would prob. focus on one girl at a time, espessially if they are related. If they were, say, just distant pals, then making one jealous of the other could work, although not totally ethically kosher 
.. In your case, I would shy away from that..
You prob. should try just wearing some Ammo around, and pretend you ain’t interested in any of them, and if they come to YOU, than it’s cool, but meanwhile, you can try to convince yourself and them that you are interested in someone else…
Good luck!
Let us know what happens.
Did I mention to wear Ammo? All the time.