The biggest challenge of writing a series finale that wraps up decades of storytelling?

Strange that I should be asked this question just now as writing a series finale is exactly what I am doing at the moment. Twenty odd years ago I wrote a series of short stories based around a river I knew well. The book (A River of Tears) was well received and so over the years I have occasionally returned with a novel here and a short story there based on the original concept. Two years ago I noticed I had written three novels and over twenty short tales of this fictional river and they were often discussed on one of my internet forums. Many commented on the fact that they would like to read more and would also like to know where this long sprawling saga would end.

I had never even considered ending it. Each novel was a stand alone, each short story self-contained there was never meant to be a finale. However, reading the comments lol- and suggestions on how it should end fascinated me. I decided to write a novel that would complete the series. Thus was “The Dead Girl and the Wandering Tree” born, but I could not resolve everything in one novel. So there will be another “Last” novel. “The Dark Kind” which I am determined will end these stories completely.

The Dark Kind, a novel by Raymond Walker

So, finally, answering the question. Drawing every character (still alive lol and one that is dead- read the stories you will know what I mean) together, is almost impossible, they have often lived years apart and some characters appear in a number of tales; others in just one or two. However, I have figured a way to complete all the “River Tales” in one last book “The Dark Kind” I have had to re-read each and every story and novel. Remember each and every character. Then invent a ploy to draw them all together. It has been absolute murder. Hard Work. Lol- not hard work like laboring or building something but hard work to a lazy-bugger author like me that normally just sits thinking and typing out some story or other. I would certainly not recommend it. My workspace is my tidy and small dining room, with a computer in one corner, a table and chairs to sit and eat at, bookcases and shelves everywhere else. The table is now covered in books open at the right pages. My desk has piles of notes and secretarial pads covering it, the chairs for the table are pulled out and covered in books, short story collections and notes, the chair backs festooned with yellow sticky notes. Even the floor has piles of books here and there. A chalk board with more notes and bullet points stands in the middle of the floor. A year ago the room was pristine. I am desperate now to finish the book.

The stories I loved so much when writing them, stories that made me cry with sorrow or joy, are now annoying. Lol- if you wish to retain your sanity; DO NOT TRY THIS.