NLW, from what I can tell, you will have to speak to a L.
What I found in my searching first points to whether there is a custody or visitation order. If so and the order states that the children are to visit, then they are obligated to do so. Even if they do not want to.
The courts would have to be petitioned to have the order changed by a judge, if the judge determines the request of the child is warranted.
Please consult with a L ASAP. Your kids might actually have to go visit their dad.