@Tanjamuse:
From what I can infer from your questions, the ABCH plug-in will totally replace your 2 custom columns and your tediously manual reconciliation process.
ABCH is all about co-authors.
It is possible you may also find value in the ABC plug-in as well, since it has an optional #abc_numeric integer custom column that enables numeric searches such as "author has more than 5 but fewer than 34 books". ABC is all about single Authors (or the primary Author when there are co-authors involved).
I suggest that you install ABCH with only a single custom column, #abc_hierarchy.
https://www.mobileread.com/forums/sh...52#post2890052
Then install ABC with both #author_book_count and #abc_numeric custom columns. Run them. View the Tag Browser for them.
See the attached image with a simple example. The value for ABCH shows the co-authors sorted from most books currently in the library to least books.
DaltonST