The best books EVER are the Berenstain Bears (well, at least I think so!).
http://www.berenstainbears.com/
If this were me, I would have rules laid out for my niece and her daughter today and enforce them (if she will not enforce rules with her daughter then someone MUST). Every day you allow this behavior under your roof, you are chipping away at any solid foundations you have built for your children. If it were my children, my niece would have a week to get serious or she would have a 30 day notice - no ifs, ands or buts. I would not hesitate by feeling sorry for her - five places in the last year should be a hint. If they did not respect my home and rules, I would not destroy my family for them. You will spend the next 20 or so years protecting your children, PLEASE start now. You can help your niece by finding her a room for rent in another home and give her a month's rent - just get her OUT of your house before you do ANYTHING else (of course, if she can change in one week, that makes a difference, but she WON'T). It is them or your family - I would not hesitate on which to choose if it were me. Been there, done that - no matter what you try, you will suffer for years and then do what you need to do - DO IT NOW! My daughters, always taught respect, were hurt badly by their cousin (my nephew) that stole from them, hurt them by "hitting" / playing, swearing, etc. We limited our time with him and my daughters felt protected and "heard". I wish things were different, but I had to choose - my daughters or my nephew - it was an easy choice for me. I cannot save the world, but I can protect my children.
