Be very careful with any type of herd share, they can be a legal nightmare. I looked into it a few years ago and was never brave enough to get involved. We plan to buy our own house cow shortly so can avoid all of the issues.
I would not even try to sell anything made from raw milk even though it is (in my opinion) safer than pastureised milk. The food safety people have said that even if it is sold as bath milk they will still prosecute if anything happens as it was intended to be sold for consumption, I will try to find the link and post it later.