When a part comes in

How do I exclude a part for a few measures and have it come in at a certain point?

To clarify: I have two soloists singing for half the song, and a third one comes in halfway through the song. All 3 parts are displaying from the top; and the bars of rest for the third singer are taking up quite a lot of space.

Layout options>Vertical Spacing>Staff visibility…

You probably want “All systems”.

P.S. Welcome to the forum!