It follows the discovery of the remains of a man and woman in the garden of a house on October 9 this year. Police have not yet formally identified the pair, but believe they are William and Patricia Wycherley, who lived at the house in the 1990s.
The couple's daughter, Susan Patricia Edwards, 55, and her husband, Christopher John Edwards, 57, appeared in court yesterday.
The pair, of no fixed address, but who are believed to have been living outside the UK, were charged with the murders of the Wycherleys between May 1, 1998 and May 31 of the same year. They were remanded in custody and will appear in court again tomorrow.