The way that BIAB treats choruses and repeats probably isn't going to work for your custom format. So do it long form. i.e. put in all of the chords for the whole song in a linear fashion. You can select bars and copy and paste them, so it won't be too hard. Also make use of the insert bars and delete bars in the Edit menu. Make sure you're set to 1x chorus with BIAB, and the end bar is set to your end bar.

I don't relate to how BIAB uses the word chorus and the repeat is only any good if you have one repeating chunklet in the middle of your song. i.e. intro - {repeatingsection} - end. It's just not that flexible.

I hope this makes sense, good luck, Mel