There are photos to prove Melo was in Houstan. I can assume there was a meeting of the minds and Melo's role was discussed.
I would think Morey and MDA discussed the validity of this trade for the negotiations took place.
Melo and MDA were reunited just months after

resigned for the 2012 USA olympic team. They made it work.
Im thinking MDA if not fine with this deal I doubt would surface this late in the process.