Star-Crossed Twins

What if Lily and James had twins? What if Harry Potter had to be raised by Severus and Jane Potter had to be raised by a newly divorced Petunia? What if there were no antagonists and everything was just a huge misunderstanding? What happens to the story now? (Humor, Eventual SLASH; TMRHP, NLOC, RWDM & Other Surprise Pairings)