Andromeda: So, maybe they fell into the black hole in the first episode and came through into a new universe?  If you wanted to keep the others (Harper, Trance, Beka, and even Rev Bem were good characters) you could just say Tyr was away when they jumped (a bad jump made them time travel, so hoping between universes isn't out of the question).  If you went with the black hole thing, Rommie wouldn't have a body, but they could build her one.