So you can't put protections on another team's pick, but can you put conditions on it? Thinking rights to swap picks, greater/lesser of, etc.
Can Celtics agree to trade the "greater of the Dallas 1st or the Boston 1st"? Then maybe even trade "the lesser of the Dallas 1st or Boston 1st" to somebody else? (Though some additional conditions would need to be added in the rare case Dallas craps out, hits the lotto, and doesn't convey their pick to Boston this year).
Say the Kings are willing to trade Cousins to the C's for the Nets 2018 first, but they're a little concerned the Nets might have turned things around by then and they want to make sure they get a good pick so they ask for the greater of the Nets 1st or Bostons 1st in 2018. Could that happen?
Could the C's say we'll allow you to swap picks with us if either of the first rounders that we control in 2018 (Nets and Celtics) is greater than your own pick? Or could C's agree to swap if the lesser of the 2 picks they control is greater than another teams pick?