A nasty family feud has erupted over music legend GLEN CAMPBELL’s $50 million fortune!

As the 75-year-old singer struggles with Alzheimer’s disease on his final tour, in­siders reveal his wife Kim, 53, has dumped several of his longtime band members – including a daughter from Glen’s first marriage – so she could replace them with the children she had with him.

“When Glen’s health started failing, Kim saw the opportunity to fire his pro­fessional band and his oldest daughter Deb­by,” divulged a source close to Campbell.

“Debby was Glen’s backup singer and right-hand gal. She’d cover for him when his memory began to fail on stage. When I saw him perform recently in Los Angeles, he struggled to remember the lyrics to some of his best-known songs and no one helped him. Debby told me later, ‘I would have made sure that never happened.’ ”

Campbell’s touring band now includes his children with fourth wife Kim – Shannon, 26, on guitar; Ashley, 25, on banjo, keyboards and vocals; and Cal, 28, on drums, said the source.

“With this being Glen’s last tour, Kim installed them in the band so they’d all have an income,” said the insider.

“It appears she’s trying to ensure that all of Glen’s money goes to her children. She’s pitting her family against Glen’s daughter Debby.”

At stake is at least $50 million in cash, property and royalties from Campbell’s four-decade showbiz career, noted the source.

“If Glen was aware of what was going on behind his back, he’d be mortified,” the insider added.

“He wanted to go out with his head held high. Instead, some of his family members appear to be at each other’s throats!”