If you were truly concerned for the well-being of the children, you would contact the authorities. I suspect that your real hesitation lies in your belief that the situation is not quite as you describe it here. Your post(s) are written in such a way to convey that the children are in imminent threat of severe harm from their father who has cut them off from the world, yet, from your place in a different state, you seem to have intimate knowledge of the minute-by-minute goings-on in their household. You also seem to be working to actively subvert the parents' role in raising their own children. You also seem to have some sort of messiah complex going on. You have stated that you are their only hope, yet you know there are resources out there that would be more helpful than what you are doing.
I really feel that you are exaggerating this matter. I just don't know if it's intentional (trolling), or if you truly believe. Either way, your actions are not helping, and are likely hurting.