Possibly OT: document composition software

Hello.

An user of mine has a need: she must produce gobs of documents which 
often comprise the same part of text (usually paragraphs or whole 
chapters), but differs in some small details or in header/footer.

That's something I would easily arrange with LaTeX, make and other 
"developers'" tools, if I had to do that myself; however I need to give 
her some more "user-friendly", non technical-oriented tool.

Bonus: these documents must be versioned; that's something she does 
manually now, but if the software would help...

Something web-based (possibly running on FreeBSD) would probably be 
fine, but a desktop application would also do (but then it should be 
able to run on Windows).

Does such tools exist? How would they be called? (I have no idea what 
search terms to use).
Any reccomenendations?

  bye & Thanks
	av.