Great suggestions so far. You might also have one night a week when your family has a movie night or a game night. Dinner can be sandwiches or a delivered pizza so everyone can relax.
If she misses a meeting, do something special with her. Make her feel "rewarded" for doing what is in the family's best interests. You could buy her some flowers, listen to some of her favorite music, dance in the living room - anything that would take her mind off the burdensome meetings.
Do you read? If you read "worldly" books, talk to her about the characters in the book you're reading, describe their struggles, and make those struggles sound like the same kind of problems JW's have to deal with. I don't think it would be a great idea to be really direct at first. Just keep it focused on the book, and let her draw her own conclusions. One good choice might be A Day in the Life of Ivan Denisovich in which there is a portion when the main character is questioning his beliefs and actually asks himself if his whole life might be a lie. I read that excerpt from the book when I was still in, and it set me to thinking!
I hope you're going to help out with the party. You might read the kids a princess story at the party. Does your daughter have any books about princesses? You can also do things like pour the punch, clear the plates and cups, or anything that would be helpful and mke the party more fun for the kids and less stressful for your wife.
Good luck with your efforts. We're wishing your family the best!