I agree with all of the above: the child should be in a diaper or pullup until accident free for weeks or a month, if the parents aren't putting in the work why should you and this is not your job, it's the parent's job. Once he is doing well at home then you can put in the hard work too. I had a little boy who just went into undies on his 4th birthday at his Mom's insistence (fantastic dcMom!) because he would NOT poop in the potty so he stayed in pullups until he decided he was ready and after that he did just great.