I’ve searched for this and can’t find anything on it in the forum, so…
In a concert band score where the key changes to E major, I wanted the Bb parts (clarinets, trumpets, etc.) to be in Fb to make them more readable. It’s easy enough to change them (put the new key signature in using Opt-Return), but they break a 4-bar multirest at that point in the parts.
[Edited] I should have made clear that there are four empty bars that begin at the key signature change; when I change the key signature in a specific staff, those four bars are broken into 1 + 3 in that staff.
I’ve putzed around with it in every way I can think of, but the multirest still breaks. Any suggestions?