Dear Ed,
You would
once type out the full time signature sequence in a variable.
You could use then the $(mmrest-of-length variable)-construct in as many voices You need.
What Kieren mentioned is new to me too and I would be curious see, how one can use these commands in a context You've mentioned.
Thanks for your answers thus far.
Kieren I think I understand the concept but I can't see a way of making that
work for what I'm doing.
Stefan likewise I think I understand but does that mean that I would need to
type out the full time signature sequence which I could then reuse for other
parts?