DBRS this week said seven firms are approved to provide third-party due diligence on non-agency mortgage-backed securities rated by the company. The companies are Allonhill, American Mortgage Consultants, Clayton, Digital Risk, Opus, RMG and R.R. Donnelley. Meanwhile, CoreLogic announced last week that Standard & Poor’s has approved the company as a third-party due diligence provider for non-agency MBS ... [Includes four briefs]