Want to know about affidavit for transfer certificate

I urgently need the official wording for an Affidavit to transfer the family car in my late father’s name to my mother’s name. We are 3 sisters as other heirs and the Affidavit is to say none of us want the car. We have been trying for a number of months to get the right advice and to do it in the right and legal way, with little success. I would be most grateful for any help!