Hi

Royal Canin do a 'Sensitive' version, I believe it is very good, although I havent tried it myself as yet.

If you can get the little un to eat some natural live yoghurt, that is also good for the digestive system. I wouldnt touch any of the commercial cat milks (or any milk) that you can buy as this is often too rich for their tummies, I would try and keep them on plain old water

Hope this helps. C.x.