Titles of submaps are included in pdf output

I have a bookmap in which every chapter references a ditamap that has a title and one top-level topic with some nested topics inside of it.

The problem however is that the title of the submap is also included when I save the bookmap as a pdf. I thought that dita titles of submaps were normally excluded from output but in FrameMaker this does not seem to be the case.

Is there any way around this (without having to remove all the titles form my dita-files)?