In a MIDI import (from Cubase in this instance).
I’ve got a quaver tied to a minim. First problem is that I can’t un-tie the tie. I guess that’s logical because the underlying midi note imported is a single stroke with that duration. So, what I want is the quaver detached and a quaver trem mark on the minim. When I try to add that, Dorico puts the single mark on the quaver, and a double on the minim.
It sounds to me like this can easily be resolved simply by removing the tie. To do that, select the note and hit U. You can actually use U from the caret to split any note at any point.
Then apply the tremolo slashes where you want them.
You can also apply tremolo slashes to an individual tied notehead within a chain of ties by selecting it in Engrave mode and then overriding the ‘Single-stem tremolo’ property in the Properties panel.