ah oke understand so it has to do with ncm that not everything works properly. apart from that, I noticed BrainFish can use two books parallel
Brainfish has a new UCI Parameter BookFile2. When playing with two Books, Brainfish first tries the Book set with UCI - BookFile. When the position is not found inside the first book, it tries the second book (if set) UCI - BookFile2 When playing with the Leela and Stockfish book parallel, the Leela Boook should be set as the first book
Another option could be to use a special Tournament book as the first book (BookFile), (which for example exploits some temporary weaknesses of other books or engines), and to use the Cerebellum Stockfish book as the backup book (BookFile2).
brainfish with 2 opening books could be even stronger than stockfish with 2 books. I’m not sure if this works with ncm but if it works you could make the engines a lot stronger.
Brainfish with the 2 opening books and with the endgame library 7 man Syzygy tablebases in combination with the functions that stockfish now has and with even more in the future I imagine myself as the strongest version that you could put together as a free version if it could work.