I know that it sounds uncool, but my girlfriend (Kim) and I are on the outs anyway. Her sister (Misty) liked me as a friend at one time, then hated me for years because we had harsh words, and now she is somewhat friendly again, but I don't think it's necessarily attraction.
What can I do to get Misty romantically interested in me. There are no more first impressions I can make, and I'm dating her sister... it's a tough one. And Misty is a naturally defensive person to boot. I need to bring her guard down. Please help. Thanks.

P.S.> My girlfriend has cheated on me twice but doesn't think I know about it. And, my intentions are not revenge - I really like, and have liked, her sister for awhile now.

The NLP approach seems that it would be most effective. I'm unsure if you have mastered it, but I don't think regular game will work. I'm sure the sister has heard everything you've done wrong and sisters tend to stick together.

A good one to use is once you have the three of them in the room. If you can neg your girlfriend in front of her and compliment the sister at the same time you can start dialog. Even try to make your girlfriend jealous of her sister

for instance if you catch her lying.

I can't believe you lied to me.. Misty wouldn't do that.

it's all i can come up with in my mildly hung over state. Good luck