For a tutorial, I need to create a flexible 4-part score:
Part 1 (flute, clarinet, trumpet), Part 2 (oboe, trumpet, alto sax), etc.
At the moment, I use separate layouts for the different transpositions (Part 1 in C, Part 1 in B♭, etc.). I add all instruments to a single player so I can display an instrument list in the template.
Is this the recommended way to handle flexible instrumentation in Dorico, or is there a better workflow for this kind of setup?
Different layouts for the different transpositions, yes. But I wouldn’t add more than one instrument per player. I’d use transposition and clef overrides for the part layouts: https://www.steinberg.help/r/dorico-pro/6.1/en/dorico/topics/setup_mode/setup_mode_layouts_clef_transposition_overrides_c.html
Where do you add the instrument names for part 1 for example @Rikard ?
Part 1
Flute, Clarinet, Trumpet, Bariton
Part 2
Oboe, Alto Saxophone, Horn
Etc
I don’t have any need for the instrument names in the score, so there I only have “Part 1” etc. (I often have an unusual balance of instruments in my ensembles, so in a simple flex arrangement I’d more or less want all instruments to be able to play everything. Otherwise I’ll end up adapting it for the specific instruments anyway.)
And I think that adding the instrument lists in the score would get crowded. One way to do it that I’ve seen in published music is to simply list the various options for each part on a separate page before the start of the music. That’s what I’d go for, if I wanted to write down that overview. (Or simply write out everything as a regular full score. That might be the best option if you’re adding in strings too and want to add bowings and different slurs on the string parts.)
And then I name the layouts with part number, instrument name and transposition obviously.
Thank you.
I could also make 4 different templates and add the instruments as text to the template. One template for part 1, and the choose the layouts for Bb, Eb, Tc, Bc etc
Ah, you’re thinking that the musicians are reading from the score, and that you have the score in different transpositions?
An alternate way of organising things that my violin teacher colleague use a lot when she’s notating traditional tunes is to not write the parts into a score but instead have one flow for the melody, and one flow for a harmony part… You don’t get the overview that you get from a normal score, but for (young) musicians not used to finding their part in a score it might be easier to read. Everyone gets the melody and the additional part(s) on their page, but separated. Particularly useful in situations where the parts are divided between melody and groove.
It depends on how you want it to look! You could do as @Rikard suggested, you could add the different instruments to each player so that each player (part 1 & part 2)can hold whichever instrument you need and then change the instrument they are holding in the score. Or, if this is to be examples within a tutorial (i.e. a page in a lesson book) you might consider using flows. If you could share a little more about what you would like to accomplish I’m sure you could get some more concrete advice. 
— Jim