There's already AND/NOT operators in tags filters. Ability to choose tags to be excluded via filters by selecting NOT would give more intuitive options to further limit the selection. Example: It's possible to choose files by selecting tags from left panel. Ability to *exclude* from operations such files where certain additional tags are used for same files would be much easier, instead of using alternative time consuming methods to be able to separate them. (Additionally selection "Images without tags" could possibly be renamed as "Images without any tags" to more clearly separate it from suggested feature.)
Found feature "Most not have this tag" but that doesn't solve all as I need to choose numerous children for one main tag and that selection is not available to be applied for all children. NOT operator would solve such problems more easily but could be counter-intuitive when combined to this feature already available.
Ok... "toggle auto" for children seems to do this so possibly nothing more is needed. Thank you!