Add horizontal frame *only* to parts
Is there a way to add a horizontal frame *only* to parts? I've got a score that I've divided into 3 sections, and the section breaks cause bad spacing in the final measure of the first two parts. I would like to make the final measure of the first two parts only take up part of the page's width, like the last measure of the score.
Is there some type of non-frame that is like a line break that allows you to adjust the right margin?