I would work with the dog in the family environment only if the dog is properly treated and fed and loved by the whole family. I agree with Logan you should also see how the older kids feel but at the same time you don't want something like this (or God forbid worse) happens.

If you have any doubts on this and you feel that the family does not interact in the appropriate way with the dog, just take him back, before they get rid of him some other way.

Whatever you do you know that we are all behind you. Please keep us posted.