I take the liberty to repeat (quote) a question asked by Joswylin in 2018, that is still unanswered:
"I'm working on a score with a 4 voice choir part. The choir asks a 4 voice part (with all voices in 4 staffs). Up to now it's impossible in Notion to create such a score with multi measure rests. That's only for individual parts. Since it's a orchestral score, the choir has to wait a lot and their score is now filled with hundreds of empty bars... Waste of paper and very hard to follow!
So my urgent feature request is the possibility to insert multi-measure rests in parts with more than one staff."