Psychotherapists are mandated by law and by ethical standards to maintain the client's confidentiality. However, there are certain limitations to the client's confidentiality (harm to self or others, child abuse, and elderly abuse). This limitation is particularly true in cases where the court appoints a psychotherapist to assess the mental status of each involved. The whole purpose of the psychotherapist's participation in a court proceeding -- be it civil or criminal -- is to inform the court of what has been said and how it bears upon the case. In cases where the court appoints a psychotherapist, the psychotherapist's client is not the individuals involved, but the court.
Because the psychotherapist had your daughter sign a release of information, I doubt if you can do much. Again, the psychotherapist's client is the court, not your daughter or you.
Sorry about your experience.