Iowa Code § 558A.5: Agency.

1. A person other than a broker or salesperson acting in the capacity of an agent in the transfer of real property shall not be deemed to be an agent of the transferor or transferee for purposes of this chapter, unless the person is granted powers of attorney or is empowered as an agent, as expressly provided in writing, and is subject to any other applicable requirements as provided by law.

2. A broker or salesperson representing the transferor shall deliver the disclosure statement to the transferee as required in section 558A.2, unless the transferor or transferee has instructed the broker or salesperson otherwise in writing.