Where facts give rise to doubts that the holder of a qualifying holding meets the requirements named in section 16, or that the connection with other persons or undertakings, on account of the structure of the network of participations or inadequate economic transparency, makes effective supervision of the insurance undertaking possible, the supervisory authority may order the holder to submit the documents named in section 9(4), point 2, letters c and d, and to have them examined, at his or her own expense, by an auditor to be designated by the supervisory authority.