Lori this sounds pretty familiar! Thank goodness you have the gargae option if all else fails! I'm sure you remember the Magoo trauma! GEESH!
I wonder why she is getting so touchy all of the sudden? Is it possible she is going into heat and the hormones are out of wack? Maybe this is why she got dumped! If this behavior continues she certainly woudn't be a good kitty for an elderly person! I think kitties are smart enough to suck us in with their cuteness and then when they have you hooked they let their true colors show!!
I hope she settles down soon because she sounds like she could be a real handful if you try to introduce her to your existing babies. I know you have so much going on with your dad right now. This could be a big challenge but as we all know after much tribulation Magoo worked out. The only advice I have is the same advice that everyone kept giving me....PATIENCE, PATIENCE and more PATIENCE!!
Good luck and keep us posted!!