Hello, leacon. My thought is for you to talk to the nurse, ideally with your brother-in-law present, to explain what is going on. The nurse may be willing to talk to your mother about the importance of following the orders of the doctor.

The nurse will then make note of what is going on when he/she reports to the doctor. You might suggest to the nurse that she ask the doctor to call your mother to explain how critical it is that the doctor's orders are followed in their entirety.

Good luck.