See clip from Attorney Rajiv S. Khanna's conference call video that addresses this question.
The question asked is can a J-2 holder obtain a waiver of the Home Residency requirement without the J-1 holder being involved and the answer is, the last time I looked into this issue it is a "No". The exemption was if there was some sort of impossibility associated with the J-1 holder conferring the benefits of a waiver for instance if they were divorced or there was a death of the J-1 spouse. In those cases certainly this was a possiblity. But otherwise you cannot as a J-2 holder obtain a waiver by yourself. Your disqualification for the Home Residency requirement came into being because of the J-1 holders status. So the theroy of the law is that J-1 holder must apply for a waiver.