3-team trades don't work like that. It usually involves Team A acquiring certain prospects from Team B to package with other players for Team C. So each team is actively involved in the process.
For example (purely hypothetical): Washington trades Morse to a Team B (that wants Morse) for 2-3 prospects (desired by Miami in this instance). Washington then packages those 2-3 prospects with 2-3 more prospects from the Nationals stable and trades them all for Stanton.
If Stanton is traded - and I believe Miami should trade him - I suspect that Nolasco will be part of the deal (a serviceable 5th starter for a year - another $$ dump by Miami - and part of the cost of acquiring a young monster in Stanton).