I’m going to go against the current here and say YTA.

Your kids tried to get to know their stepsiblings and they resisted because they have a huge (for children) age gap. I really can’t understand why you see a problem with that.

You also have no right to be upset that they don’t see you as their parent. You’re not their mom, their mom is alive and well. I suspect that there is a lot more that happened that you’re not saying here. Did you try to force being a mom on them?

You don’t have to act like a parent to build a loving relationship. So a 10 years old tells a therapist that they never will see you as their parent and you decide to just stop trying to bond with them?

Also, what were the circumstances of the divorce?

They are obviously not entitled to a trip to Europe. However, if they are asking their mom to ask for custody there is obviously a lot more going on.