Sorry! Hit the wrong button and sent the message prematurely!
I meant to say that Sarah's burial record is :
29 Apr 1866 Sara McDermott, Parks
There is a death for a Sarah McDermott on the online civil death records site which gives her age which ties in with the birth of James and Sarah's daughter b. 1851.
Death: Sarah Mcdermot, age 15, 1866 Kilkeel Registration District Volume 6 Page 483
There is also what appears to be the death of her sister Rose Anne (for some reason the priests in Kilbroney parish did not list the burial records of young children)
Death: Rose Anne Mcdermot , age 6, 1866 Kilkeel Registration District Volume 6 Page 483
Rostrevor/Kilbroney is located in Kilkeel registration district.
Parks is a small area just outside Rostrevor on the road to Hilltown located in Kilbroney townland. Newtown (I wrote Milltown by mistake in my previous posting) is just over the way from Parks, so they may have moved there some time after Sarah and Rose Anne's death. You can order these certs from
www.groireland.ie - it is cheaper to order the photocopy rather than the actual cert.
There is also a burial record for an Elizabeth McDermott :
9 Jan 1877 Elizabeth McDermot, Newtown, aged 61.
Unfortunately I cannot find her death on the online death records, but I believe not all deaths are up on that website
https://familysearch.org/pal:/MM9.1.1/FRPK-24Q You would be able to order the cert from the GRO in Belfast if you visit there in May.
This Elizabeth could be James' sister going by her age.
Sorry that I could not be of any real help. Kilbroney is my native parish and I am very familiar with these records and the Morrison surname is not a common one in that area. It is probable that they moved from another county to Rostrevor in search of work, so don't discount Dungannon, Co Tyrone. There is a Roman Catholic parish called Dungannon in the diocese of Armagh. Their records start early (1826) and you would be able to access them at PRONI.