Hi everyone thanks for your replies.
We have tried telling off the bitch, as firm as I can. This makes no difference. She has just decided that Max is now ready to be dominated.
As these episodes mainly occur when they are snuffling around the floor for food, I have started shutting them out of the room completely when we are preparing and eating our food. Also I have started to split their own meals into two, instead of just once a day.
So far so good. The atmosphere is a little different but I will see how things go.
Thanks everyone for your help.