For me personally I never get rid of one family to make room for another. If I cannot accommodate the new family then I don't take them. I don't want a bad name for myself and I stick to my word. If I said I will take a child part-time then so be it. I am stuck with that until they leave. Don't forget, the grass isn't always greener on the other side. 2 new kids might only stay a month or be terrible kids/difficult family etc no matter how great they seem on their interview.