Agree! I always "teach" my maid in front of my husband, so that everybody is clear of her mistakes and requirements. Probably this time you can 教訓 the maid together with your mother, so she knows she has to get instructions not only from you or your husband, but all your family members!
your maid is really "idiot". Po po is really smart. Frankly speaking, my mama is not as smart as your mother. My case is the PK inin assisted my mother to take care two babies, 2yrs & 3mths. This PK inin pleased my mother at the very beginning and always turn her long face to me because she thought my mother would protect her. My mother did not know how to control maid. I told the maid that she could not sit the sofa and our bed but you know she sat comfortablely at my mother's sofa and sat on the bed when she was doing iron in the room. My mother did not tell me until I fired her. She also requested my mother to buy her this and that when she did shopping in supermarket with my mother. Worse, when I went to work after maternity leave, she reported to me that how my mother treated my baby, (spoke ill behind my mother), how stupid those inin. Finally, my mother told me that she did not want to see her any more, then I fired her. See, your mother is already a smart Po po. I hate those PK make use the kind heart of old people. My new maid will come very soon, I told my mother to be serious to her otherwise, she will repeat the same problem.