Tricky second-level contrast

Dear CoNN experts,

Even after checking the very good examples of the conn manual regarding second-level contrasts (attached), I've been stuck with the following contrast:

I have two groups of subjects (A and B), and each subject underwent a resting-state session Pre and Post treatment. I have some behavioral variables that had Pre-Post changes. I would like to know whether some Pre-Post connectivity changes were related to those behavioral changes in the whole sample. In other words, I am interested to perform some kind of "delta clinical - delta connectivity" regression analysis, in order to investigate whether the post-treatment clinical changes that we observed were driven/associated to connectivity changes after treatment.

Thanks a lot in advance!