Nurses taking orders from physician office MAs in Texas

We work with a physician who insists on conveying orders through his office MA in one of our Texas facilities. Several nurses are refusing to take the orders. The Texas BNE stated they no longer address this issue but leave it to the hospital's standard of practice. The Medical Board referred to the Administrative code which also does not address the issue either. Other facilities in the area do accept his orders, but have no written standard.

Looking for a standard of practice, or information that addresses this issue.