Glen Campbell has excluded three of his eight children from his will.

The music legend behind songs such as 'Rhinestone Cowboy', 'Wichita Lineman' and 'By The Time I Get To Phoenix' passed away at the age of 81 in August, and according to documents filed in a Nashville court, the singer decided that three of his kids will not benefit from his estate.

Glen - who was married a total of four times - fathered eight children but Nashville's Tennessean newspaper reported his 13-page will, dated September 2006, excludes the three offspring from his second marriage to Billie Jean Nunley - which ended in divorce in 1976.

His daughter Kelli and sons William Travis and Wesley Kane will now not be able to benefit directly from his estimated $50 million estate.

The filing also excludes his children from a related trust but a hearing is set to be held in January which could start off a protracted legal battle over the terms of the will.

Glen was married to Diane Kirk from 1955 to 1959 where he fathered his eldest daughter, Debby.

After his split with Billie, Glen married Sarah Barg in the same year and the couple had one child named Dillon but they split in 1980.

The lothario then had a high-profile relationship with Tanya Tucker but proceeded to marry Kim Woollen in 1982.

They had three children together, Cal, Shannon and Ashley.

Glen's cause of death is said to have been a result of his 2011 diagnoses of Alzheimer's disease, with which he fought a ''long and courageous battle''.

Glen was inducted into the Country Music Hall of Fame in 2005, and released his final album 'Adios' - which was a compilation of covers recorded prior to his retirement - earlier this year.