"We have and will always miss having a husband, dad and brother at these family occasions, and we hope someone, somewhere, has the compassion and humility to come forward to help the police and our family."
It is believed Mr Sibbald was murdered in the hours immediately after his disappearance and his body dumped. He had suffered multiple stab wounds, Lothian and Borders Police said.
Detective inspector Scott Cunningham said: "We firmly believe that the key to solving his murder lies in the local community and we are appealing directly to anyone with information to come forward and help Billy's family put his memory to rest.
"We understand that people may have previously been reluctant to approach police with any information they had at the time of his murder, however we recognise that with the passage of time, people's personal circumstances and loyalties may have changed, and they may now be willing to share any information they have with us."
Mr Cunningham said a number of items of clothing and jewellery that Mr Sibbald was last seen wearing, including a distinctive lighter, have never been recovered. He said these items are featured on the force's website - www.lbp.police.uk/ - and urged anyone who recognised them to get in touch.