KC - you'll need to split it into two bars. Our program manual has an example for 6/4:

...we will split the 6/4 bar into 2 bars, a 4/4 bar and a 2/4 bar. Insert a # beats per bar =2 at the beginning of the 2/4 bar, then restore the time signature to 4/4 by assigning # beats per bar =4 for the next bar


You can find more information about this in the Settings for Current Bar topic at https://www.pgmusic.com/manuals/bbw2024full/chapter6.htm#song-editing-features

(page 135 of our PDF manual shows an image for this https://nn.pgmusic.com/pgfiles/support/misc/manual/bandinabox_win_2024_printable_manual.pdf)
-Callie