Your parents are being influence by their mental regulation meetings and association with confidential members within the WT setup.
The stand off situation doesn't work. Stay close to them and exert your own influence. It is much greater than you can imagine. You have something that they value beyond words - your children.
Help them to understand the difference between fantasy and the reality of what they can see and hold right now in the real world - their grand children. Their grand children's genes are the closet thing to immortality that they will ever know.
All the best.