In terms of the court order, it's interesting that everyone is suggesting that now they're teenagers they can do their own thing but if he wasn't adhering to it, and not facilitating their visits to her, that would be an issue, right?
Your Dp has the responsibility to not block contact on these weekends. So no taking them away, without prior agreement or stopping them going.
But no court is going to demand teenagers attend visitation if THEY do not want to or demand they stay for the whole time. And if they did, how would it be enforced? The police won’t pick them up and force them to stay, if they don’t want to be there.
Honestly at 13 and 14 they should be telling their dad where they are. A court may not be happy that no one knew where they were when they were in her care. There’s potential for social services to be involved, but again, at their age, there wouldn’t be a lot they would do. it’s unlikely they would try and stop the kids seeing her at all. And your dp doesn’t want that as he wants his weekend off.
If, at 13 dd was with her dad and decided to stay at a friends, I would expect her to tell me. Not her dad.
There seems to be lots of issues here. The main one being the teenagers refusal to communicate with their Dad. He needs to sort that. But facts are that as kids get to teenage years, they get more say over what they are doing and where they stay. Many decide to stay more at their main home. If they are at home alone, as they came back early, then they should let their dad know if that’s what he wants. But there’s really no big deal with them, at their age being in their own home. There’s no need for him to rush home.
Remember this isn’t about what’s fair on your dp or their mum. The courts will, where possible listen to older kids.