Change Stave name part way through a score

My Score starts with 4 staves, (1st Tenor, 2nd Tenor, Baritone, Bass),
Part way through the score, I need to change to 2 staves (Tenor 1&2 and Baritone/Bass)

How do I change the stave names, without changing globally ?

Note that toward the end of the score, I need to change back to the 4 staves (1st Tenor, 2nd Tenor, Baritone, Bass),
Thanks & Best Regards
Reg