Does the Divisi function response to the number of players?

Does the Divisi function response to the number of players?

Such as in the attachment, the horn section varies from 1 to 4 players. The 4th player is indicated with stems in opposite direction to the III (3rd) player.

You’re probably better off using Condensing than Divisi for this.

Yes, certainly you should use condensing and not divisi for this. Divisi is for taking a section of players, like a violin section, which is normally written as a single voice on one staff and then splitting it unto multiple parts across multiple staves. Condensing, on the other hand, is for taking a number of soloists, like four horns, which are normally written on separate staves, and then showing the music on a smaller number of staves if it’s possible to do so while retaining legibility. Dorico handles both uniquely well, but it’s important that you use the right tool for the right job.