ID series of novels science fiction....sisters turned into cow like aliens, mother ship full of humans

I'm looking for a series of books that deals with humans escaping Earth and having a mother ship full of humans who are being sent throughout the universe to different planets. they ship can transform the humans into whatever type of alien the planet holds. one set of sisters is transformed to cow like aliens and sent to spy on that planet. all the while the group that's taken the mother ship full of human colonizers is trying to evade/escape the government people from Earth.