🚀 go-pugleaf

I think that the method Thomas mentions (text insets) would be a good start toward what you want.  Logical pieces of content would sit in separate files.  Your FrameMaker chapter file would act as an integrator, bringing the appropriate content files together in the correct order.   

Your strategy assumes that you have a good method of file management that would carry over to help you manage topics/content.  I am sceptical about using file management in this way; our current systems are rooted in archaic, implementation dependent (disk-based) models.  

I feel that XML will be more likely to offer what you need for topic/content management.  You would create tags to define topics and the structure of topic content.  You could then browse and edit your XML document or documents in a tree or outline view.  XML will allow you to directly specify whatever information model your content follows, without the unnecessary intermediate step of chunking content into a file. 

An interesting book with strong opinions about files and content is Jef Raskin's The Humane Interface. 

Regards, 

Everett