Write to Dept of Vital Statistics in Massachusetts to get a form to request a birth certificate on her. You have both parents name and it may cost you $20 to $30. This will verify that she was born and give you more information on her. On form where it asks your relationship, put sister. Don't go into specifics. That is how I got My BM birth and death certificate. If you go go a Massachusetts government page it will give you an address for Dept of Vital Statistics. Hope this helps.