triangulation

I have just read about this in Boundaries by Dr Henry Cloud and Dr John Townsend. I feel open adoption or reunion with a teenager where aparents are invilved is triangulation in the making. For example I read so often where the amother is saying that the bchild is not ready for reunion and telling bmother stuff that bchild is saying. Then bmother is responding to amother and on it goes. So the amother is in the middle and bchild and bmother never talk direct. Ultimately it is very unhealthy. Authors say that the way to avoid triangulation is to always talk to the person with whom you have issues etc first. 'never say to a third party something about someone that you do not plan to say to the person himself.' In my OA I have realised that my bchild has probably said things to amother that should never have been passed on to me. Has anyone else come across this?