Just wanted to update, and thank everyone for their advice.
DP and I spent a long time talking about the best way forward. He understands what I was saying, I think I probably phrased it wrong at the time. He's been going back and forth to courts for the whole of our relationship, and the stress that causes is unbelievable on its own.
He felt like he was getting it from all sides. The solicitor was presenting our options in moving forward, and when he relayed the information to his family, they started pushing him to apply for residency, which I find highly odd, as they don't see his dc - that's a whole other post! But with all them telling him we can do it, and must do it, there I was saying I think we need to think about how we would go about this, and is it the best thing to do at this time. Add in a giant solicitors bill, two frustrated court dates- a solicitor change, and a 'miscommunication' -, and a high conflict ex, the school are saying that she has told them that he is not to collect them, and despite seeing the court order, they're following her directive, and he felt like there was nobody on his side. I think perhaps we weren't communicating properly on any of the issues as well, and I had no idea that he was feeling pressure from his family, while at they same time they forgot to invite him/us to several family events - birthdays, celebratory meals, etc.(Whole other post!)
He needs to talk to me more about everything that's going on, and I need to show more understanding. It can't have been easy to hear that people believe your dc are in danger of psychological damage, and I don't think I showed him that I understood it was hard for him. I felt that it was a decision we shouldn't make on emotion, and I took all emotion out of it, and of course, it is a hugely emotive subject.
We've also talked to a whole load of professionals. We're trying to come up with coping strategies for him to use when he has to deal with her. We're also looking at ways to minimise the impact of her alienation on the dc.
We have talked with my dc about the situation, and how they would like to see things move forwards. I've spoken with both of their schools about the ongoing court drama. I feel that as they spent a large part of the day with them, it would be helpful to have other people keep an eye and be aware of the issues. My DS's school have been incredibly helpful. They're talking with him about blending families, and have been an invaluable resource of information for us.
He's not going to seek a change in residency right now, because it would in all probability fail, but there are agencies involved now to move things forward. He agrees, and so does the solicitor, that a failed application is likely to make her even harder to deal with, and she probably would move again. He has a court date in January, so is seeking 40% access, with the hope that the judge will put penalties on her if she breaches again.
I feel like we're on the same page with it, which I think was part of his problem anyway. I think he was feeling almost exactly like how I felt, but then had everyone telling him it was the right thing to do. If she had passed away, there would be no question. Likewise, if the court ordered it right now, there would be no question. From my point of view and his, but doing it this way, it feels like a big thing, and not one we would win at this point.