The J.W's are frustrating/impossible to debate with. Stephen Law in his book "Believing Bullshit" which I recommended on a thread, has as one of his eight methods used to teach, or justify, B.S "Moving the Semantic Goalposts".
He points out this is a method much beloved by theists as well as others. He says, and I agree, this is a totally intellectually dishonest method of argument, and one that invalidates your argument, even if what you are arguing is in fact true !
Perhaps you could get your friend to read the book, but I doubt she will love the title, also people are not good at applying criticism to themselves, worth a try though.
Try to be kind and honest in the way you limit, or end your friendship, in other words tower head and shoulders above the way JW's treat people.