with your duaghters well being at stake, you CAN and maybe should tell her what her daughters are saying...however perhaps letting your daughters know, or asking them if it would help might be a key piece in doing so.
Look if either one of my boys were feeling down because of my wife's actions, you can bet your assuptions I'm going to say something to her.
Now...how I say something to her depends on the lay of the land.
Remember Bills and Kids, still have to communicate with her about.
Experience is a brutal teacher, but you learn. My God, do you learn. - C.S. Lewis
Life is usually all about how you handle Plan B. - Jack3Beans
Listen without defending; Speak without offending - FaithinAK