You are absolutely correct with your suggestions. My SIL and brother though are not approachable (I just can't comprehend his having to deal with this but I have noticed he simply chooses to block out the behaviour altogether). I do speak up on occasion and it results in awkwardness (ie. that's no way to speak to your mom, watch your language, etc) and my brother and SIL most definitely fail to appreciate it. Yes, I spend time with other family members apart from family get-togethers; so, it hasn't resulted in and estrangement. I have begun to find ways to gather ahead of time whether or not she will be in attendance. For instance I will say to my brother, "I need numbers for dinner."

Thankyou for your suggestions. I suppose I will have to find some tactful way of approaching my brother.