For formulas for those with MPI it can depend. A small percentage of those with MPI/MSPI can tolerate the cheaper hypo allergic, partially hydrolyzed formulas like Nutramigen or Alimentum which still have milk proteins that are broken down (like casein) but no actual "milk". Next is the very expensive formulas like Neocate and Elecare which some people can get coverage through their insurance for. These are amino acid based formulas so avoid the partially broken down proteins. There is also soy formulas but a lot of those LOs with milk intolerances also have soy intolerances as the proteins are quite similar.
It's is a nice website describing the different formulas
http://www.kidswithfoodallergies.org/resourcespre.php?id=140&As for the alternate milks there is rice milk, almond milk, coconut milk, soy milk, and goats milk. Soy and goats milk have proteins that are similar to milk proteins so are something to be wary of, but are also the closest thing to milk nutrient wise . I would also suggest doing research on the other milks if you are looking for something more than just adding milk for texture, so using the milks for more of their nutrition.
HTH!
