She probably planned on doing what she had always done with Amy--just increase the elaborate lies she was already telling. She could tell Amy she needed the money because her parents impending "divorce" and that when she bought a house, she'd let Amy stay for free to pay her back.
I think KC had no fear of repercussions from Amy. She was blatant in how she used Amy, repeatedly, and figured she would once again talk her way out of it.
The following is my opinion based upon text messages:
I think she was mad or jealous of Amy in a passive-aggressive manner. When you look through the text messages you can see a pattern of Casey wanting Ricardo's attention, and then complaining to Amy of not getting it. Casey starts weaving the web of lies about maybe Amy moving in with her at the A family home (and CA and GA would be somewhere else!). Once Casey meets TonE she blatantly (in my opinion) uses TonE to get at both Jesse and Ricardo by introducing them to TonE like within the first two weeks she physically meets TonE (more than strange in my mind). Once Casey gets hung up on TonE she starts texting Amy about how Ricardo is all into her and the irony of it that now that Casey likes TonE that Ricardo is opening up to her. Once the jig starts to be up about Amy not moving in with Casey (either at the A home or some rental home off Conway and Michigan) then Amy (who is now in quite the predicament) ends up sleeping on the couch at Ricardos. The next night after Amy sleeps on the couch here comes Casey back to Ricardo for a few nights in a row! If you read the text messages in order they are really revealing.
Then regarding the PR trip. It would seem that once Casey realized she wasn't going to be going to PR with Amy, Ricardo and all the gang she took the opportunity to allegedly steal the $400 cash from Amy (and used the "sleepwalking story"). I think Casey was jealous that Amy was going to Puerto Rico (almost "in her place") and I think that Casey did not like Amy sleeping at Ricardos (even if Casey already had TonE). I bet the fact that Amy was in PR and she was not made her feel even more entitled to Amy's money.
Just my opinion...
[Some of the texts]
May 19th AH text from Casey Anthony: Ill be in a place by then. You can stay with me. Im looking at a place tomorrow with my mom that i might be signing on.
May 20th AH text from Casey Anthony: That would help im sure! Theres an inground pool with a fenced in porch and backyard. Its a great starting house.
May 21st AH text from Casey Anthony: He just complains about stuff to me all the time but changes his mind in an instant. Whatever. At least the last couple times we have hung out not a thing has happened [Casey b*tching about Ricardo.]
May 23rd [More b*tching about Ricardo] AH text from Casey Anthony: Well if he calls me a again we cant be friends. Im serious. I have never argued with someone like this outside of my family and at least then it wa
May 27 AH text from Casey Anthony: I almost feel bad because ric invited me over like 4 times. He decides now of all times..after i finally got closure with him to start showing me that he cares. Grr.
May 28 AH text from Casey Anthony: Thats perfect. If anything once we move my stuff into my parents room we can use my room for storage and the garage too. There will be plenty of room.
May 30 Amy in Tallahassee. Ricardo says Casey and Caylee sleep over.
June 2 Casey tells Amy and Ricardo (at different points) that she made out with Tony.
June 4 Casey Anthony wrote to Amy on Facebook: oh, the times we will have! i can’t wait for us to become roomies in another week! seriously… by the end of next week, it will be just us girls. i can’t believe it
June 6 Casey is supposed to have dinner with Ricardo but then does not show up and claims she had to work. Ricardo later sees the Fusian pics on her myspace.
June 7 Amy moves in with Ricardo.
June 9 Casey and Caylee show up at RM's around 8 p.m.
June 10 AH text from Casey Anthony: He finally decided to tell me that he loves me.. and unfortunatly im not there with him anymore. I waited for months for this to happen and now that it has i cant say that he is the only guy i have feelings for. Its like i have to choose. Hes throwing everything in my face. Ugh
June 10 AH text from Casey Anthony: He wants me to still date him knowing that im starting to like tony. I cant do that. Im not that person. I respect him too much to do that.
and so on..