Placing endnotes in a complex document

The standard endnote usage in nonfiction publications is: Each chapter starts endnotes at number 1. Endnotes are placed after all chapters and before the list of references (bibliography). I am currently writing a book using this placement. I write each chapter as a separate document for various editing reasons, using my own template which puts the endnotes at the end of the section, and I put a section break/next page at the end of the document. When I'm ready to assemble a full draft, I use a frame template that I created that has a section called "Endnotes" with a section break placed there. This is followed by sections for the appendices, references, and the index. I use Insert File to place all  the chapters in the frame document.

My technique used to work, until the most recent updates. Now I can do one of three things:

1) Endnotes are placed at the end of each chapter, and restart at 1 with each chapter.

2) Endnotes restart at 1 with each chapter, but are placed at the end of the document and nothing can be added after them.

3) Endnotes are placed where I want them - all together at a specific location - but they are numbered consecutively.

None of these does what I want. If I have to, I'll live with #1 and let a publisher straighten it out, but it's always better to hand in a fully prepared ms. (I also want running heads, but I'll worry about that later.)

Support has opened case # 1009353894 for this problem, and referred me to this community for further support.

Thanks ,

Dan