Just wonderng how many litter boxes are in the house? With six cats the ideal number would be 7. Food and water should never be near the litter boxes. Also the younger cat could get picked on by the older cats. You seem to be allowing the kitten free run of the house? Have you followed the "Introdusing cats" article in the behavior section at the top of the page? This will greatly reduse the stress this little one will go through. A bathroom is too active an area for your kitty and she should be moved into a spare bed room if one is available. This will allow her to decompress and relax. By grabbing her and force feeding her you are just adding to the stress and keeping her too upset to eat. Please read the article by clicking the "behavior" button at the top of the page, scroll down to "I'd like to introduse" about bringing home a new cat to a house with cats.