The pop star pals sued John Wilde in 2009, claiming he had been interfering with the sporting rights connected to their Glenmore Lodge estate.
Hucknall and De Margary bought the main house and land in 2005 and relaunched the Glenmore Rivers Sporting Estate.
However, Wilde insisted the land they claimed was theirs had been transferred to his father by the previous owners.
A hearing of the case was scheduled to begin at Letterkenny Circuit Court on Monday (24Mar14), but lawyers for all parties have stated that an agreement has been reached.
The Simply Red stars were not in court and details of the settlement have not been released.