I have no idea about her upbringing.....but to me, it looks like her parents were right about not liking her boyfriend. He doesn't seem like a good person, to take his daughter to another country behind the child's mother's back. That's not behavior any parent would want in a son-in-law.
But, even if her parents were meanies, so what. She's 21. You want to get away from your parents? Fine. Go. But don't leave them at the airport gate and create chaos for them like a coward and brat.
Okay, I'm going to quit complaining about her. Just find the little child and bring her home safely. That's the priority.
(Of course I hope NC is safe too and at this point, I'm assuming she is a willing participant in this dumb stunt.)
jmo