Horrible separation situation advice please - please read its long?

Ok first of all I have been there. He is prob not full of hot air, I thought the same when he made the threats but he wasnt he took off with my 6 week old son while he was watching him and I was at work. First of all ur sister and her kids need to go some where he knows nothing about. Then get a restraining order. The next time he treatens to take the kids call the cops she will get a court date in a week and they will issue a restraining order. MAKE SURE IT IS FOR HER AND THE KIDS. Tell them that he is what they call a flight risk. While the restraining order is in place she needs to go file for custody. Most likely she will get because of the restraining order against him. And honey you tell her to take everything that man has... down to his last damn pair of socks! If he breaks the restraining order he will automatically go to jail which I think he deserves to be. As for the other woman I understand she doesnt know her but there isnt much at the moment she can do. She just need to explain that her and daddy didnt get along to well and that there may be some new people in there lives, that they may not like thatm but Mommy will always be there for them to come home to. Now if she mistreats them such as hitting I would also call the cops that wouls also be grounds for a restraining order. Tell her that she is a strong beautiful woman who can not hide behind the shadows of a man. They are no longer together he has no say so in what she does. And remember after a certain point... A man can only do to us what we allow them to. And I think her point has came. And the kids may be heart broken for not seeing there dad for a short period of time but how much more heart broken would your sister be if she never got to see her kids again. Good luck!