6 year old boy with bulimia?

Although he might meet enough of the necessary criteria to be officially diagnosed as bulimic I don't think for a child this age it's appropriate to approach this problem that way. What you described with the other boy being fostered by friends sounds like classic "stuffing." The vomiting is just an after effect of feeling the need to do that. I personally would refuse to let someone call that bulimia. It sort of is, but really isn't. Purging implies intent. That doesn't seem to be what the goal of the child was at all. He was into whatever the stuffing was giving him (which usually revolves around fear or anxiety). In that case, his desire to do that needs to be resolved and consequently the rest will too. The chances that he's dealing with PW are astronomical. Just in what you've wrote I'd be confident in saying that is so not what's going on there at all. There are no details on the boys you've been approached to take, but again, I'm not sure I buy into the belief that bulimia, and what it actually represents, can exist in a 5 year old. More than likely he's got attachment or anxiety disorders that are manifesting themselves via the vomiting. On a personal note, when I was a child if I drank soda I vomited. I had an extremely sensitive gag reflex and just a bit of a burp bubbling up would cause me to toss everything I'd eaten in the last three weeks lol. Didn't stop me from drinking soda, especially if there were other kids doing it. I didn't want to be excluded and I liked the way it tasted. That didn't make me a bulimic. As an adult suffering from generalized anxiety disorder simply stepping into a restaurant was/sometimes still is enough to make me vomit. Not because I want to, but because the chemicals in my brain go into overdrive thinking about the social situations I'm about to undertake and it's a side effect of that. That doesn't make me a bulimic either. Just like a child stuffing and consequently vomiting doesn't make them bulimic. Unless the entire intent IS to vomit, and that can be confirmed, I cannot stress enough that the problem can NOT be approached from that angle. Approaching it as the actual problem instead of merely a secondary symptom of something much larger isn't going to get the child anywhere. An EI evaluation would likely set things straight and get the kiddo on the right track to overcoming this issue and the root causes of it.