Triangulation refers to when your primary aggressor has their associates perform social pressures (sometimes without them applying much themselves.)

For lack of a better example, consider the aspect of Shunning in some religions/cults; If the leader thinks someone is out of line, word quickly spreads, and the entire group will focus their behavior on making the target feel unwelcome.

Source: dealt with more culty shit than I ever wanted to, which is why these movements creep me out so much.