Is this really that difficult to understand? What do you see when you look at Jesu, Joy of Man’s Desiring? I see all the instruments but one written in 3/4. The Violin 1 part is written in 9/8. I see the two parts aligned with nine quavers in the Violin 1 to every six in the other instuments.
I’m suggesting that one could tell Dorico that that’s what one wants to do by entering the following into the popover for the violin part:
9/8 : 3/4
One would be entering a time signature and a ratio. That means the time signature is to be 9/8 and that it should have the duration of a normal bar of 3/4, Is that not what you see when you look at the Bach?
One could choose to write Jesu, Joy of Man’s Desiring in 9/8 and then every instument but Violin 1 would have to have the time signature 3/4 : 9/8. Obviously it would be perverse but the point is that it’s the ratio of one metre to the other that matters. A signature and ratio of 3/4 : 3/4 would be indistinguishable from a standard 3/4 time signature.
Do you really think faking the 9/8 with triplets (as one has to do at the moment) is preferable? Is what I’m suggesting not exactly what one would be thinking when writing music by hand? Would this system not offer amazing ease and flexibility?