I would DEFINATELY have a conversation with her parents and another with your D16 before they go. I do believe W will use their time together to try and get her "on board."
COUNT on it.
I can "guarantee" that this is her plan. Diffuse it before she gets a chance. This may also be a perfect time for D16 to give her some MUCH NEEDED truth darts.
Lost, this is why I wanted you to do this two months ago!!!
