What's chaos to you may not be chaos to her. I think you are over analyzing this. It's your sister; she wants you to stay with her.
I agree. Why overthink it? It's a nice gesture. Even if you feel that in her shoes you wouldn't be able to handle additional "chaos", to her it might feel like a good way to spend time with you.
Sarah
When it's easy, ride hard; when it's hard, ride easy.
2011 Volagi Liscio
2010 Pegoretti Love #3 "Manovelo"
2011 Mercian Vincitore Special
2003 Eddy Merckx Team SC - stolen
2001 Colnago Ovalmaster Stars and Stripes