Hi Grohatgi -
Of course, I'm sympathetic to your child's condition, and applaud your efforts to "get the word out", and I understand the difficulties of performing clinical studies on rare diseases.
That being said, a few comments on your edit -
I'm not a pediatric gastroenterologist and I don't have any particular expertise in the disorder, but my pubmed search did point to a recent review article from Mayo - http://www.ncbi.nlm.nih.gov/pubmed/21691116 that worded the evidence behind antibiotics (such as vancomycin, metronidazole, etc) as having "biochemical improvement" - but failed to go further than this.
Another review http://www.ncbi.nlm.nih.gov/pubmed/20393280 states that "Prolonged oral vancomycin treatment may be beneficial in difficult-to-treat PSC associated with inflammatory bowel disease"
These statements are both guarded and significantly watered down from "oral vancomycin is an effective treatment for pediatric PSC". In the encyclopedia, I think we can only state as fact what we have good evidence to support. Again, I know this is tough when there just isn't much hard data out there.
I also suggest you take a look at the medical article manual of style (MOS:MED) and the common pitfalls section. The article is intended for general readers and shouldn't shouldn't be worded in a prescriptive way - "pediatric caregivers should..." I certainly hope that people making these kind of decisions about treatment aren't looking to Wikipedia for guidance!
I think a statement along the lines of "limited data in children with both PSC and IBD suggest that there may be benefit from oral vancomycin" would be reasonable.
I hope that helps! Good luck.