Two Client & Therapist Calls - Audio Problem on 1 remote end

Tried to do a three way call today for the first time. The Doctor could hear and see both clients using a broadband modem on the doctors end, and two cell phone connections for the clients. The clients were in two remote locations (cities in different states). Both remote clients could hear and see the therapist. Both remote clients could see video of each other and the doctor. Unfortunately, while both remote clients could hear the doctor, they could not HEAR each other. Had to terminate the visit. It was a couples counseling session, where hearing and seeing each other and the doctor was necessary. Also, the switching back and forth (video) created audio glitches as well, and was disconcerting to the remote clients. Is there any way to toggle between this switched half duplex mode, to a mode where the therapist selects who is seen and heard? Also, and more important, and do we fix this so both clients can hear each other, even if there is a lag on video switching?