Most of this thread began with a very concrete problem and question, way back here: Shorten (all) systems with fewer bars - #7 by Doug_Walter
A number of forum members very kindly offered their own solutions, and all my subsequent questions have been in relation to carrying out those solutions. Because I am far less experienced with Dorico, there are numerous gaps in my knowledge, which makes carrying these solutions out difficult – hence my many follow-up questions.