Adding (and subtracting) voices on the fly

[Gordon Gilbert]

Hi!

I'm doing a Bach fugue, the most of which has three voices throughout, and 
I began by using a template for SATB, eliminating the bass voice.  This 
seems to have suited about 90% of the piece, but there are parts where my 
"alto" part should more properly be printed on the bass staff (and it's 
coming up on the treble with ledger lines).  I also have some places where 
four parts are written (I promise I will learn it!).  Without having a 
whole stretch of rests from the beginning, is there a way to introduce 
(and later stop) a fourth part, say by referring to measure numbers?

Blessings,

Gordon Gilbert


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