Key signatures of music in minor key for transposing instruments

Intro - basics
Alto sax is a transposing instrument. Alto sax is in Eb meaning when it plays a written C it sounds Eb, a sixth lower.
The issue
If I want to have the alto sax score in Eb minor, I would expect the key signature of the sax music to be in Gb. (Enharmonically D# minor would have a key signature of 6 sharps - F# major). I can get Dorico to create a concert pitch A major score and a sax score in F#, but can’t see how to force it to Gb.

Has anyone an idea - please?

Remarkably, this identical question was asked by someone else only 11 hours ago.

Thanks Mark,
I had not found the previous post, but it does suggest there is a need gor this capability.