My ten year old daughter was diagnosed with ADHD
in kindergarten. She has tried to use her ADHD
as an excuse or a crutch but it is my job and her teacher's job not to let her. She can try all she wants to but she 's not going to get away with it. Yes, please tell your sister that it is in her son's best interest to seek the advice of a professional. It may not even be ADD; it could be something else, but at least you will know and be able to do something about it.