IMOO - even if the other 4 children are taken into care (foster/adoption), they would have a better life than they had and would have with their biological parents. Foster carers and adopters in UK are (in my experience and knowledge), generally doing a wonderful job in caring for children who have traumatic/abusive pasts. I guess and hope that the older boy goes to his polish family as they will take care of him better than the abusive and violent father and stepmotherI agree. In his interview with the BBC, his emotion was palpable when Sara was mentioned.
I also think it's slightly unfair for people to malign the grandfather as a liar. I believe, his intentions were to do what's best for the children in the difficult circumstances. Going on the run and into hiding would obviously not have been in their best interests, neither would handing them over to authorities in Pakistan without knowledge of where they might be kept / taken after that. If I were in that situation, perhaps I would have done the same if only to protect them and ensure they were safe.
And, in fairness, the police were looking for the three POIs. That was their brief. Perhaps the police on the ground "informally" knew where the children were all along (but, again, what could they do with them). In hindsight, perhaps this was the reason they were only detaining Urfan's relatives and not Batool's (?) because they knew the fugitives would be maintaining contact with their children(?)
Also, have mixed feelings about the children's immediate future. Glad they're safe but what are the prospects for their return to the UK. Batool appears to have been estranged from her family so the children will not know them? In any case, taking on four young children (assuming N is reunited with his mother) is a lot to cope with, and we don't even know if relatives in the UK would be able to do that (they may have disabilities etc.). A life in care is a grim option as well as the prospect of splitting up the siblings.
JMO
JMO