Eileen Rosaline O'Connor, who died 99 years ago aged 28, is about to begin the second stage of the path to canonisation after being declared a "Servant of God" by the Vatican in 2018.

On Thursday, 128 years after her birth on February 19, 1892, the Catholic Church in Australia will formally announce the members of a commission to oversee her hoped-for beatification and canonisation.

This marks the start of a process to find evidence of her "holiness" and verify miracles attributed to the woman called Little Mother to support her further elevation.

The focus on O'Connor has been a long time coming.

For years she's been regarded as Australia's "saint-in-waiting", following the canonisation of Mary MacKillop, founder of the Sisters of St Joseph of The Sacred Heart, in 2010.

O'Connor also co-founded a religious order, although she was not, like MacKillop, a nun herself.

There are other similarities with McKillop.

O'Connor was also born in Melbourne. She too formed a spiritual partnership with a priest who helped her co-found a female order, suffered the suspicions of the local church hierarchy, clashed with Rome and was threatened with excommunication (although MacKillop actually was).

Unlike MacKillop, O'Connor suffered a lifelong painful affliction that left her bedridden or in a wheelchair.

In 1897, when she was five O'Connor was diagnosed with curvature of the spine - later determined to be spinal tuberculosis.

The toll of the disease stunted her growth so she never grew taller than 115cm, or three-foot nine.

The pivotal year was 1911, when her beloved father died of cancer aged 46 after the cash-strapped family had moved to Sydney and was living at Redfern.

The tragedy led to her meeting a priest, Father Edward McGrath, a Missionary of the Sacred Heart serving in Coogee in Sydney's east.

In the following months, Fr McGrath helped the family find cheaper housing in Coogee and it was during one of these moves that O'Connor became unconscious from the pain and - according to her writings - began to have visions of Mary and Jesus.

Our Lady's Nurses for the Poor was co-founded soon after by O'Connor and Fr McGrath with the aim of creating a community of nurses to help the sick in the homes of the poor who could not pay.

"This little lady was able to achieve far more in 28 years than most able-bodied people," Archbishop of Sydney Anthony Fisher said.

However, the Brown Nurses, as they were known because of the colour of their habits, weren't formally approved as a diocesan congregation of sisters - or nuns - until 1953, decades after O'Connor's death on January 10, 1921.

But their numbers have dwindled over the years and the order is now under the governance of the Sisters of Charity, who established Sydney's St Vincent's hospital and girls college.

A mass to mark the formal opening of the cause for her eventual canonisation will be held at Sydney's St Mary's Cathedral on Thursday.

Australian Associated Press