Tying Scottish folks back to Irish roots

Perhaps you might give approx years for John, Julia, and children?

When did they go to Scotland?

Were children born in Ireland or Scotland?

What religion were they?

Thanks.

As Patricia has said we need more information. When were they all born? What do the Scottish censuses say about their places of birth? Did they have any children born in Scotland in 1855, or 1861 onwards? (Any 1855 certificate should tell you where the parents were born and when. 1861 onwards should tell you where the parents married. If in Ireland then obviously that should help a lot. When was John junior born? Where and when did the parents John & Julia die?

 John Duffy was born sometime between 1795 to 1810.  Probably married Julia before 1833.  We believe their son John was born @ 1833.  There is a long and continuous line of John Joseph Duffy's.  Religion Roman Catholic.  The son John is in Hurlford/Riccarton, Ayrshire, Scotland by 1861. (census & marriage record).   He marries Margaret Gaffney formerly of Roscommon in Kilbirnie, Scotland in May 1861.  On the marriage certificate, John's parents are listed as Julia Graham and John Duffy, a laborer.  There are no Scottish records, I could find, that indicate John and Julia are in Scotland. I'm thinking they were dead at the time of the marriage or were still somewhere in Ireland or had already died in Ireland. 

John dies in Scotland and Margaret and all the children emigrate to the U.S.

I have the Scottish records of son John and Margaret's children born, deaths, etc.  It is the Irish part I am having difficulty.  Where did they come from in Ireland and how can I trace them?  I've looked at every public record I can find in Ireland looking for a John Duffy and Julia Graham but have had no luck.  All the family knows is the Duffy's originated from the north of Ireland.  I also recognize North Ireland had a different boundaries than they have today.

I have been successful in tracing the Gaffney's of Roscommon, so those records are complete.  Are there any Landowner/Lord's records that may have captured a John and Julia Graham in Ireland?  The other children's names I included as they are the recurring names in future generations (Andrew, Stephen, Mary, Bernard, Julia, Thomas).