Sir Paul McCartney's estranged wife Heather Mills has reportedly signed on to tango on hit US reality TV show Dancing With The Stars. The one-legged former model-turned-activist will replace Sharon Osbourne in the upcoming TV contest, which will also feature former 'N Sync star Joey Fatone, Billy Ray Cyrus and Muhammad Ali's daughter LAILA ALI. Insiders tell US TV show ACCESS HOLLYWOOD Mills will donate her earnings from the show to an animal welfare charity.