4.5/4 time signature

Is it possible to create a 4.5/4 time signature in Dorico?

I’m afraid not, no.

(Obviously you can create a 9/8 time signature, though it’s not the same thing.)

9/8 will do for now. Thanks!

This is a very narrow set of circumstances, but if the entire piece is in 4.5/4, or if you never need a 9 as the top value and 8 as the bottom, you can simply use a 9/8 time signature then edit it. In the image below I just used 9/8, but then edited Music Symbols/Time Signature 9 to be 4.5, and Time Signature 8 to be 4. Not super useful in a piece with multiple meter changes, but it can be done on a limited basis.

I recently did this in Dorico for the same situation, worked great, fully supported option.
4.5 - 4.png

I still don’t understand how you did this. How do you edit “Music Symbols/Time Signature”? I don’t see this anywhere. Where do I find this?

The Music Symbols Editor is available from the Engrave menu (in Engrave mode).