why complicate things?
From what I understand you believe that the Canucks want Hughes over anyone but are scared Hughes won't be there at 7, Meanwhile Montreal is torn between Kotkaniemi and Zadina.
Just have an agreement in place that Montreal drafts Hughes with number 3. If they do that, Kotkaniemi is guaranteed to be available at 7, since Zadina still has to be picked from 4-6 (he's not going to fall to 8)
Just have the Canucks draft Kotkaniemi at 7, and trade the players, not the picks with like a 2nd and a 4th next year for Montreal's troubles or something
Trading the picks are risky for Montreal still, since between 4-6 Kotkaniemi, however unlikely, can still be drafted at which point Montreal just dropped down 4 spots for nothing since they didn't even get the guy they wanted. Yes, they would have Hughes, but not an immediate need.