Functional Equivalent of Word's "Master Document?"

Is there a way to create a "Master Document" (along the lines of a Master Document in Word) such that the master document will automatically import dozens of smaller FM files at specific places in the master document to form a new composite document.

The specific use-case is where you have a technical manual for a product and want to include several (sometimes dozens) of sections that provide generic descriptions of some features, intermingled with product-specific sections. So you'd want to be able to create a skeletal "master document" and then "render" it and have it import all the pre-fabricated sections from separate files.

Unfortunately Word's master documents have been unreliable for years -- even to the point where they damage the sub-documents during the process of assembling the master document. There be dragons...

So what I'm looking for is something like C/C++'s #include function, except that in this case, the included material is shown.

It might exist in FM, but I've not been able to find it -- I do know about conditional text and variables but at first blush they are not an elegant solution to the problem as each prefabricated section needs to exist as a separate file.

Assembling the "master document" by hand is, of course, feasible, but is likely to induce insanity after several iterations!

Anyone solved this problem, perchance?

Cheers

Andy