Can be done Rog !! Provided you are willing to create a style in the Composer
A silent break can be implemented as a 'Fill-In' and can be any length from 1 to 16 measures. You could even have say Fill-In 1 as a single measure silent break and Fill-In 2 as 2 measure silent break.
Rather than actually create a completely new style, you could just copy one of the existing built-in styles to the Composer and then edit the Fill-Ins as required by clearing all the parts in the Fill-In and setting its measure length to whatever 1 measure, 2 measure etc.
I've used this method a few times.....