Sanghamitra and Bokaro express were originally MAS based trains that were extended later to SBC and ALLP. SR is unlikely to accept a bid for diversion of these trains. And in addition, these trains are the only daily trains from MAS to Patna and Dhanbad.
Bokaro was diverted via Perambur for a short time in the late 90's and that decision was met with severe protests back then, because of which the diversion was cancelled. That could also be another reason why they aren't interested in diverting these two.