Just a thought, but are you sure the kids mother would let them go? In my experience, when it comes to the crunch they will hang on to them. Sometimes if only to p*** the father off. My partners ex did just that and that was 15 years ago. Many moons ago and after many court hearings and financial hardship my partner gave up fighting for custody, only 4 years later be begged by is ex to take the child on full time as she had screwed up his upbringing and he was totally out of control. I was not prepared to take him on then at 12/13 yrs and make my 4 kids suffer. There is nothing wrong with saying no. You took on your partner, yes with the baggage but you did not agree to be a foster mother. If he wants them to live with you then he should make the sacrifices and take care of them. Your girls are of an age where you can have more of your life to yourself, stick by your guns and explain why to him. Bet he would not have given his job up when you got together to look after your daughters. You are not being horrid or nasty, I dont think he is thinking the whole thing through properly, I think step mums get a raw deal, the blokes always expect us to take up the role, no questions asked and its not fair. good luck