I've created for my posts a custom taxonomy named "subjects" as a non hierarchical. I have some categories defined (and category itself is a taxonomy).
I want that each group of terms in the "subject" taxonomy, will be able to attached only to specified categories.
Let's say - if I choose category A. so I would be able to choose subjectA1, subject A2, subject A3 etc.. and if choose category 2, I would be able to choose subjects as subjectB1, subject B2, subject B3 etc.
How such a linkage between terms of different taxonomies, can be done?