Can you post a screenshot of what you have?

… The piece is in 4/2, but I've manually split each measure in half with a dotted barline, using the Plug-in for "split measures".  The parts are more readable this way.

But in the process, I seem to have lost the ability to make multimeasure rests.  Is there a way to tell Finale to use multimeasure rests with split measures? …

Josh Mitteldorf,

Are you an experienced Finale user?

I am not sure how detailed instructions you need.

If I understand you correctly, each 4/2 measure is split into two 2/2 measures separated by a dashed barline, right?

Unfortunately I am unable to duplicate your problem.

I am able to create multi measure rests all right.

You have not (by mistake) selected {Break a Multimeasure Rest} in the Measure Attributes?

However, the multimeasure rest counts each 2/2 measure as one measure.

Example:

Three 4/2 measures are counted as six 2/2 measures.

To fix this you could hide the (incorrect) number, and add the correct number as an expression.

That sounds like you might have to set up your score first without the divided bars.