Hi Shelley...I'm so glad you read the DocWithin site, it's such a good primer.
I think that the b&p drinks would be the gentlest....they are just very innocuous and benign. No extra herbs or anything. Just a physical drawing in of toxins and scrubbing out of the intestines. I think that is your sister's best bet for colon cleansing, yes.
I'm glad to hear that the Liver Flushes are improving your health, that's great!
I have begun to pass out this post I found on Ulcerative Colitis - it looks pretty promising!