Grogan from County Tyrone

Hi Folks,

I am trying to locate a birth/baptism with parents and siblings of my 4th great grandmother Isabella Grogan/Gruggan etc who was said to have been born in the county of Tyrone, Ireland before emmigrating to Australia according to a passenger list and marriage and death certificates for her.  She could be born anytime between 1827-1830 depending on which record I use for her.  No Parish or Townland known.  This is what I know:

She arrived at Geelong, Victoria aboard the ship "Wallace" on 16 Feb 1844 as Isabella Gruggan age 23 year old Roman Catholic girl. On the same voayge as Isabella was another Grogan family as follows:

Henry Grogan 26 husband Labourer RC reads Tyrone, Mary Grogan 26 wife RC reads Tyrone, John Grogan 4, Ann Grogan 2 and Henry Grogan 0 RC Tyrone.  Father Henry Grogan died 1845 aged 25 at Newtown, Victoria and no parents were recorded on his death certificate.  Is there a family connection between my Isabella and this Henry Grogan? 

Isabella married  Jacob Ponton in 1846 in a Roman Catholic Church in Melbourne and their first child they named Henry (possibly after Henry on the same ship).  Isabella and Jacob had 4 children and the last child being the only girl was born 28 Sep 1853.  Husband Jacob disappears sometime shortly after Isabella falls pregnant with Mary Jane the daughter.  There are no parents recorded for Isabella at time of marriage to Jacob. Daughter Mary Jane dies by 1854 and Isabella later marries a man by the name of Patrick Rodgers in 1862.  On this marriage certificate her parents are recorded as James Grogan (Farmer) and Ann Rodgers.  However, on Isabella's death certificate in 1882 her parents were listed as unknown Gruggan and mothers' maiden name formerly Rogers.

What are the chances that my Isabella and Henry are siblings or cousins from around the same Parish/Townland?

As for Henry and wife Mary, I found a Marriage on ancestry under Ireland, Catholic Parish Registers 1655-1915 in Deseretcreight, Armagh for Henry Grougan to Mary Donaghy come Donovan.  Henry would be born around 1818 based on his passenger list and death age.  I think that the time period could be out for both Isabella and Henry when it comes to a birth/baptism.  Henry and Mary's last child born in Ireland was Henry (jnr) where I found on www.rootsireland.ie a baptism for 21st May 1843 at Dungannon, Tyrone.  Sponsors were Arran and Isabella Mcglone (could Isabella's surname be mis-transcribed from Mcgrogan).  Parents were recorded as Henry Grogan and Mary Donaghy also known as Donoghue and Donovan.

Any guidance and assistance in finding something on my Isabella Grogan would be greatly appreciated.  I have been trying to trace this for the past 32 years.  The closest I have come is the possibly of Henry being connected.

kind regards

Sharon Kirby