I just didn't know how to handle her ..
This is my feeling when i saw how cleverly SIL is handling MIL .She got the technique of it and throws back the tantrums and wishes of her mother back into her own way and also gives a piece of advice to her in the process and thats what MIL needs.Some one who can dominate her in the way she tries to put her way through things about other people .And SIL is superb that way .Hats off .