Auto-opening Van sliding door scratched by my already open SUV door. Who’s at fault?

As my wife was putting our daughter in the back seat of our SUV, the people parked next to us utilized their auto open feature as they walked down the parking lot. The sliding door on their Van begins opening and comes out about 6" and proceeds to pin my wife partially inside our car while she has a grip on our two year old that she's buckling in. In the process of not being able to release the two year old and attempt to slide out, the door continued to drag itself across our door edge and left a good streak of white paint embedded in their dark paint.

The driver contacted me today for my insurance info as originally he said he may know a guy to take care of it but is now saying his wife is going to get a quote done.

I don't feel like we are at fault at all because if the other driver was with their vehicle they would have responsibly noticed someone in between the two vehicles and not opened their sliding doors. The worst part of their neglect is that our trunk hatch was open wide so they knew there was potential activity at the cars but still decided to open from a distance. I also feel the paint streak shows that their vehicle door was in motion, not ours, upon the damage occurring. I figured I'd ask since I can't find a definite answer and need to be ready if I have to prove all this to the insurance or if this is something they've seen on a common basis? I'm worried about my rates going up as I've never had a claim against me before.