Mary Hillas : Short Biography

Hi!  This is my first post here so I'm just figuring out how this works.  I have been tracing my father's family through their lives in Scotland and all but one of my father's great great grandparents were born in the North of Ireland.  I have managed to find some clues online as to their Irish origins and I have a lot of questions I'd like to bring to this site (which, by the way, I think is wonderful).   I thought I'd start my digital expedition here with Mary Hillas.  

My father's great grandmother Rebecca Connelly emigrated to Glasgow and married George Crossan in Glasgow. She was probably born about 1838. I have also found her brother Patrick Connelly in Glasgow, born about 1837.  Scottish census information tells me that Patrick was born in Downpatrick. Rebecca and Patrick's marriage and death certificates tell me their parents were John Connelly, a blacksmith/agricultural worker, and Mary Hillas.  By the time of George and Rebecca's wedding in 1858 both parents were deceased.

A John Connelly of Downpatrick married Mary Hillas of Ballygowan at Magheralin Parish Catholic Church, in the diocese of Dromore, County Down on 24 April 1820 (Source:  https://sites.rootsweb.com/~rosdavies/SURNAMES/H/Hi.htm).  Shortly after the wedding, their first child was born/baptised. 

8 May 1820 Philip Connelly  Ballygowan, County Down, Ireland

If these two are the parents our Rebecca then I assume they must have had a few children inbetween Philip and Patrick being born in may then have moved to Downpatrick where their further children were born including Rebecca and Patrick.

Obviously Connelly is a common name.  I have found the following who may or may not be connected. 

I have found a John Connelly, a blacksmith from Downpatrick who has moved to Whitehaven in Cumberland.  (son Hugh born c.1867 in Downpatrick, Mary Margaret born 1886 in Whitehaven)  He was born in 1844 to George Connelly. I wonder whether he might be a grandson of John and Mary and a nephew of Rebecca.  John Connelly married in Downpatrick on 15 April 1866 where he married Susan Taggart daughter of John Taggart. He had a son George 2 March 1871 in Downpatrick. The baby died in 1871. There was a Hugh born in Downpatrick in 1866.  This John's father George might provide more information if he is another brother to Philip, Rebecca and Patrick. 

I would like, if possible to learn more of Mary's heritage.  I understanding tracking John might be more difficult.  I'm also interested in finding other brothers and sisters of Rebecca who may have made their way to Glasgow.  

I'd be very happy to have any advice or other help.  Once I have done as much as I can online, I hope to visit to see the places that my ancestors lived in.

Many thanks for reading :)