putting 'boxes' under subheadings

I’m using the boxes feature on pagelines.

I would like to be able to have different boxes under different headings on the same page, but I can’t figure out how to do it. I have done it in the past, but since upgrading my site have no been able to do it again.

The page I am using it on is a list of staff members with a headshot linking to their bio. I would like to group the staff members according to their position.

I am able to group the boxes into ‘box sets’ but I can’t find a way to separate these sets and give them a heading on the actual web page.

any help would be great.