Jaimee, I'm with Sara in the setting rules and boundaries even if you have to be stern. Making giant messes does happen, but I would not tolerate pulling things out of cabinets while someone else is looking, just for the sake of making a mess. I know your kids are a little crazier than mine, but have you tried being more stern in setting boundaries for the younger ones? Its a hassle and there would be a learning curve, but not letting Avalon be self sufficient because her brothers would be in her way making messes seems like it could be detrimental to Avalon learning to take care of herself. Independence is huge for development of self care skills, and it sounds like she is not able to be as independent as she could because of her brothers. She is a VERY bright girl and is probably way more capable of taking care of things on her own than you are giving her credit for (or giving her access to). Can you put up a gate to keep them out of the kitchen while she makes herself snacks and breakfast? Or even while she makes ALL the kids snacks or breakfast. My oldest is a bit older than Avalon, but DD1 is her age. About dressing- yes, I just sent DD1 to dress herself and she came out in a tank top and SHORT shorts, so I told her it is cold and she needs to wear long pants and at least a tshirt. She may not always match, and she throws some interesting accessories in there (boots and skirts, tutus over jeans) but she dresses herself and its a great outlet for self expression.
Abra thats great that there is still a family interested in the bus. Sound VERY hopeful, they seem serious!