Cordelia.
Googlemagoogle was the first person to reply to this thread.
He's (She's?) right. Your Dad has the choice to make.
Your Dad needs to know that YOU will always be there for HIM.
Agree never to talk about JW's again and be honest. Don't bother trying to prove WT wrong. They don't want to know and it makes you appear a threat
Play the same game and say that they are welcome to visit you anytime to see their grandchild.
Never let them see their grandchild without you being present. Take control. Make them make the decisions. If anyone is forced to do something that they don't want to LET IT BE THEM