Will Dorito support Multiple Time Signatures in the same file? i.e. one instrument in 3/4 while another is in 5/8 or 4/4, etc. If so, will we be able to have the option of lining up say, 4/4 and 12/8 so that the quarter note in 4/4 equals the dotted quarter in 12/8 AND/OR conversely, line up the eight notes in both meters conventionally? Where an instrument might be playing a cadenza, freely, with lots of notes, and the orchestra playing something more simple, which should not line up with the soloist, will it be possible to squeeze the cadenza into a smaller space, without regard to note spacing? How will measure numbering be handled in these situations?
Thanks!
Frank
See this thread: Multiple Tempi and Time Signatures - Dorico - Steinberg Forums
I found that pretty quickly by searching for multiple time signatures.
The short answer is “not in the first version, but it’s in our plans.” Further to Bryan’s reply, more details about time signatures in this earlier thread:
A lot of scores written by very important composers have this feature. I hope that it would be possible at least hiding a time signature and adding a graphic one, as it’s possible in Cubase Score. But this requires additional manual work on beams, graphics tuplets and so on. 
If Dorico doesn’t yet support multiple time signatures, how did Göran Valter Arnberg write his Etude Polymétrique? Did he have to resort to tricks or does he have a preview version of Dorico 1.0.10?
You can have different time signatures on different staves, as in Etude Polymétrique. If you use the right-hand panel to select a time signature and Alt-click it into the score, it only affects one staff.
But in Dorico 1.0 the note durations on every staff are identical, so you can’t have 4/4 and 12/8 on different staves with the bar length the same on both staves, which is one of the things Frank1941 asked about.