Boyle, 48, dubbed Hairy Angel, is not allowed to perform on any other show until Britain's Got Talent has finished, but her friends and relatives have told her to talk to the TV chiefs about letting her start her career.
A friend of Boyle's said that the singer is on the verge of ripping up her contract and going it alone, as she fears that she may be missing out on millions by not cashing in on her fame now. "The chance of earning serious money doesn't come often and now it's in danger of slipping away," the Daily Star quoted one of her friends as saying.
The Scottish singer has to wait almost five weeks before she next appears on the programme, and her ultimatum demanding the right to make money immediately from a record or a tour will throw the show into chaos.
"Finally she has the chance to show the whole world her amazing talent but she isn't being allowed to," Boyle's brother John, 59, raged.
"When Susan signed a contract tying her to Britain's Got Talent before her audition, no-one could have predicted what a phenomenon she would become. The normal rules don't apply any more, and I think Simon Cowell knows it too. This is a unique situation and needs a unique solution - and soon," he added.