You can force the number of bars in a line by using the Lead Sheet Options|Fakesheet bars/line. Many of my songs have 1st/2nd endings and I play with this to make the leadsheet look like I want. Often times, I have to use values such as 4,4,6,4 to give me the desired results. In this example the leadsheet will have 2 lines of 4 bars, 1 line of 6 bars, and the rest will be 4 bars.

Maybe this will help

R