My team creates reports that are hundreds of pages with approximately 1,000 endnotes. We use the InDesign (2015) Book feature, with multiple chapters as separate files. Each chapter can have upwards of 100 endnotes. The compiled Endnotes are a separate file at the end of the Book. The Book feature updates page numbers (dynamic), but not TOC numbers, table numbers, figure numbers, or endnote numbers. Our workaround has been a very cool plug-in called Fnote for endnotes, and InSeq for tables and figures, both from Sonar Bookends. The plug-ins update all numbers sequentially according to the Book order. The TOC still has to be done manually.
Each Word file gets imported to InDesign, keeping the Word endnotes (dynamic - add or subtract an endnote, and INDD will renumber). Using the plugin, the endnotes are cut to a different INDD file, keeping them dynamic. 10 chapters, 10 endnote files. Once the Book is created and the INDD files are placed in order, the 10 endnote files get cut and pasted, in order, to a new composite file that will go in the Book. When "updated," all endnotes will dynamically be renumbered in the Book, as well as all references!
Sonar Bookends has discontinued the endnote plugin!! The last was for Adobe CC 2019. We are upgrading to Adobe CC 2020. We have to upgrade the InSeq plugin, but what options do we have for dynamic endnotes!?!
I was referred to a 2017 question that dealt with the same basic issue to avail: