I was chatting to my American friend last night who is also a divorce and custody attorney and obviously I had to ask them about this
It sounds like this isn't going to be as clear cut for Sophie getting full custody of the kids in England. They also don't believe she found out via the media - both she and her legal team would have been served with papers once Joe filed. Part of the provision of the Florida filing is that the kids remain in the US for the duration of the case so the Judge is very unlikely to allow the kids to return to England while this is all ongoing.
Either way, it sounds like this is going to get worse before it gets better. What a horrible situation for her.