A 19-year-old man from Woodend, north of Melbourne, has been revealed as the so-called "back up" miracle in the canonisation of Mary MacKillop.

As a boy, Jack Simpson developed multiple sclerosis, cancer and epilepsy and lost his intellectual capacity.

His mother, Sharon, says when there was nowhere else to turn, she started a series of nine-day praying cycles to Mary MacKillop.

She says the miracle occurred a year later when her son regained his intellectual capacity.

"Medicine wasn't able to help us at that stage in our life so we needed something special and that was Mary MacKillop," she said.

"It's like people who suffer from Alzheimer's and that sort of thing, once you've lost that competency of that part of the brain you don't get it back and Jack did."

The case was presented to the Vatican as a back-up to the second miracle needed for Mary MacKillop to be made Australia's first Catholic saint.

Mary MacKillop will be canonised on October 17.

Meanwhile, the New South Wales Lands Department, together with Mary MacKillop's order, has released a booklet of title deeds bearing the sister's signature.

Lands Minister Tony Kelly says the documents will show how the nun helped her order flourish.

He says the idea for the booklet came from Lands Department staff.

"It occurred to them there must be documents around with her signature on it as the order bought and sold land for convents and churches and schools," he said.