I can’t believe you’re calling your DIL selfish for not wanting you to take her kids away from her. No you don’t see them but if you try to take them away from their mother, it’s you that is the selfish one. They’re not your children. I understand your DS is the father but he did not grow these children inside him, he did not feel depleted of energy for 9 months to give these children the nutrients they needed and he did not put his life on the line to bring them into the world.
Is it an unfortunate situation? Yes. But you need to keep out of it, stop offering unsolicited advice and leave your DS to organise things with his partner.
If you behave like this now and her visa does eventually get granted, I expect your access would be restricted no matter where your grandchildren live because no DIL wants a grandparent to act overbearing and entitled. Please remember you are talking about HER children.
Being quizzed by chemist's assistant in Boots.