I've already described what a potential Melo-to-Boston trade might look like. If Melo wants to play with Rondo so bad, he should demand a trade. The Knicks are at a bigger risk of losing Melo than Boston is of losing Rondo. Rondo has 2 years left on his deal... Melo can opt out this summer.
Jeff Green, Bass, Lee, Wallace, Humph and multiple 1st round picks for Melo and Amare's corpse. Ask for SHumpert too, but settle for whatever junk min-level contracts they add as "filler". Seems fair to me.