hi Masonry Guy, thank you for your patience. I actually made some printscreens, to show the structure of the main-category and the subcategories, but I could not figure out how to send them with this message. But I got wiser studying the images myself, so I thought I’ld give it another try.
When I use the category__not_in=112,113,114 the result is that my posts with category 112 are filtered out. The other ones are still in.
I think I must drop they idea of filtering out the maincategory. I think I’m going to use the meta_key and meta_values, like I did abusively in the first place. Thank you for thinking with me!