The Kallah’s family was involved prior to you getting divorced?
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As far as the actual question, I can’t answer. I think it may be worthwhile to discuss it with a child psychologist or social worker that deals with children.
G-d does the payment for those who have wronged us. Sooner or later. You can be assured of that.
For your kids, you have to do whatever is in their best interest. If these people will rub it in your kids face over the next ten years that you prevented them from attending… Maybe the opposite, let them go for the Kabolas Ponim and Chuppah. After that, home to a delicious supper, ice cream , a big hug and yummy bedtime story and bed.