How is the father wrong here?
He thought his kids were going on a holiday. They didn't return. I suspect if it was the dad who had taken his kids on this holiday and didn't return then there'd be a far greater outcry, especially on this website.
Both Italy & Australia are signatories to the Hague Convention which compels Australia to return the kids to Italy. And thankfully so too. Without the Hague convention we'd see far more parents disappearing with their kids to another country.
And if your OH/DH kidnapped your kids would you .."lay criminal charges?" Of course you would. Would you withdraw them? Probably not. By promising to do so, at first glance it does seem dad is the more reasonable one. I'm not sure I could be so gracious. It took all my self control not to kick my ex's door down when she refused to return my kids to me. Those who have never been refused contact of their own kids will never understand.
It would seem from the 2nd link that the main reason the girls are resisting going back is because they've been unfairly influenced by mum. Kids are kids at the end of the day and it's easy to manipulate them by feeding them a diet of how bad dad is, how much trouble mum will be in. How she can't live without them etc etc.
From where I'm standing mum is firmly to blame here. She should have fought this in Italy. She fucked off to Australia, prompting a big legal battle and then made the entire thing public in an effort to garner public sympathy.
I'm glad it didn't work. To allow her to have done this is the thin end of the wedge.