Before I forget, I wanted to tell you that Joseph Marnell's family was also from Lisburn. On the 1901 Census of Ireland, his parents (his father was a constable (RIC) and siblings were at
15 Market Place in Lisburn and on the 1911 Census of
Ireland, they were at 4 Ava, Lisburn. My grandfather moved to Belfast when he got married, and when his wife (my grandmother) died, his address was 21 Alloa Street, Belfast.
My grandmother died at Mater Hospital in 1917. They got married in 1910, so he was not married very long. That hospital was very close to Alloa Street, according to a map
I looked at. Have a good evening and good luck at PRONI.