I need to switch of one clef to two-clef!

Hello everybody!

Can you tell me if it is possible to switch from a staff with a single clef to two clefs (violin and bass) within the same score? I am writing a book and I need to insert examples of musical pieces written for the treble clef and others in the treble clef and bass (piano staff).

The problem is that if I choose at the beginning to use only one clef and then in the next exercise two clefs, all the exercises turn into staves with the two clefs!

Is there a possibility of being able to switch from one clef to two within the same piece without having to save and reopen a new score to switch to a two-clef staff?

Thanks for your help!
LouLou