Mel, 39, was announced as the fourth judge earlier in the week, and had been tempted back with a reported £1 million contract.
The singer cut ties with her family in 2008, after it was alleged they did not like her husband, Stephan Belafonte, and accused him of being violent.
Stephen, 38, allegedly attacked a former partner, before he married Mel and the family are thought to have worried about his behaviour.
And even when the former Spice Girl renewed her vows to the film producer, a year after they wed in 2007, her mum, Andrea, dad, Martin and sister Danielle, reportedly called it a “big mistake”.
According to reports, the infighting meant the mum-of-three did not attend her grandmother’s funeral last month, with one of her aunts telling the Mirror, “Mel was close to her when she was little but not since she’s grown up. She was off to LA and lived a lot of her time there, so she didn’t come.
“We do follow what she does. The rift is mainly between Mel and her mum. Things have been said and I can’t see any reconciliation.”
Mel, who’s set to the return to the judging panel next week when the audition stage of the competition kicks off, has been approached by her family before, with her sister Danielle saying in 2012:
“Me and the whole family are so worried about her about what’s going on. It’s not a person I know. She doesn’t sound right.
“This whole drama has never been about money. This was not how Mel was raised. I just do not know who this Melanie is any more. It’s just sad and upsetting. I want my big sister back.”