Cher might be adding “grandma” to her legendary résumé — and if this long-buried family secret is true, it came with a plot twist straight out of a soap opera.

Former model Kayti Edwards is claiming she dropped a bombshell on the pop icon last year … telling her she shares a daughter with Cher’s son, Elijah Blue Allman — a kid Cher allegedly didn’t even know existed for more than a decade.

According to Edwards, who spoke to The Sun, she and Elijah had a brief relationship back in 2010 that resulted in the birth of a daughter named Ever. She claims Elijah always knew about the child, but never stepped up as a full-time dad … allegedly popping in every few years, but keeping his distance from parenting duties.

“She was speechless,” Edwards alleges … adding Cher told family members, “Oh my God, I’m finally a grandma.”

Despite the rocky backstory, Edwards says things have warmed up since then. She claims she and Ever were invited to stay last September at Cher’s Malibu home, where the singer played host — and proud grandma. Cher reportedly showed Ever iconic stage outfits, asked about her life, and even splashed around in the pool like a kid herself.

Still, the family drama isn’t slowing down. Cher last week filed again for conservatorship over Elijah, citing serious concerns about his ongoing struggles with addiction — which she says are at their worst.

Add in Elijah’s recent arrest for alleged assault and trespassing, and it’s clear this family saga is anything but simple.