multi-instrument (simultaneous parts)

I am writing a strange piece where the two players switch instrumentation.

Player 1 is playing drum set in the first movement, and then switches to bass guitar, but occasionally also plays kick drum along with the bass.

Ideally I’d like to have the two staves bracketed together in the 2nd movement, and I’d like the kick drum (whole drum set staff is fine) to appear in the part w/ the bass. (hidden most of the time, since it only comes in for a few bars)

What’s the best way to set this up?

You may find that pretending your one player is two players but then include both the drum and guitar lines in one Player layout and hide the empty staves where either is not needed.

You should be able to add bracketing in Engrave mode with the bracketing tool.

Are you asking this question because you ran into some trouble, or before even trying? Because I think that Dorico should behave by default as you describe, if I understood you correctly. Try it!