"Olivia's bodily functions appear to be shutting down, but she refuses to let go until she makes it through Chloe's wedding day!" a source told RadarOnline.com.
Reports claim the singer is committed to spending her final days at the ranch she shares with husband John Easterling in Santa Barbara, California.
They have not been confirmed by the singer's representatives.
The Grease star was diagnosed with breast cancer in 2017 and also has a tumour in the base of her spine.
Olivia has managed to overcome the disease twice.