I am putting together a multiple chapter book with a master document and I have run into the challenge of referencing Figures, Tables, Alphabetic index and bibliography across separate subdocuments (chapters).  The notion of creating a "Set Reference" and using "Insert Reference" for cross-referencing between subdocuments is not only awkward and clumsy, but requires that you create your own "database" of reference names.  Having done that, when you "insert reference" you can get the chapter number and the text that was highlighted when you create a "set reference."

There are multiple challenges with this approach.  If I attempt to "set reference" to the caption on a Figure, if I attempt to highlight the word "Figure" I find that the figure itself is selected and would be pasted in when I do an "insert reference."

I know that this is not strictly the purview of the documentation team but might be better addressed as an enhancement request for the operation of the Libreoffice Writer implementation team.  My suggestion is as follows.  Every time I perform an "update all" from a "master" document, it would be nice if there were (optionally because it can be time consuming) the ability to create a database table of "set references" that is browsable in the same manner that "Headings," "Figures," and "Tables" can be browsed when you perform a normal "cross reference."  The database table would be segmented by the sub-documents known in the "Navigator" at the time of the "update all" operation is performed.  Then I could scroll through the list and select the heading, figure or table in the same way I would do in a single large document.

This database would literally be a file so that it does not consume large quantities of memory.  When I select an item from this list, it would automatically "tag/create" in the source document the "set reference" that is required and then perform an "insert reference" in the target document.

This would not be simple or easy, but is simpler than building my own table of "Set references" that can't handle the different types of references.

Most of the necessary code exists when index tables are generated.