I like the ROP-lite mechanic.
It sounds like a trick I've done in the past. Hand the ball to the thrower-in just as B breaks the huddle, and they have to jog to play D. Or put the ball down when the thrower-in is "almost there". If they are paying attention, they will get the message with little to no effect on the possession. But continually hanging around their huddle and using your voice is craziness, imho.
There are officiating tools available. Use them.