Sorry to hear about this. All I can tell you is it takes time, sometimes a long time for cats to adjust to each other. Maybe you could try taking a towel or blanket that Misty is using and let Squeekers smell if for a little while to start getting her used to Misty's scent.

Hopefully some others here will have better suggestions.

Good luck. I know you would hate to have to give Misty up.