I guessed it was Dublin because it's the only Sandyford I know.
Catholic registers for Sandyford and Glencullen for baptisms until 1904 and 1905 respectively and marriages to 1909.
https://registers.nli.ie/parishes/0527
Do you know when your great-grandparents married and when the 2 children were born? Are you sure all theses events happened in Sandyford parish?
As your great-grandparents are presumably deceased you can tell us their names and dates.
If the 2 children are also deceased you can give their names and possible birth years. We're not allowed to name people who may be living.
According to the 1911 census they had been married 2 years which i assumed would be 1908 but most likely early 1909 as their first child was born Dec 1909.
There doesn’t appear to be any baptismal records for the 2 children born in Kiltiernan but there are baptismal records for the children born in a booterstown later on once they move.
So I’m pretty much stuck! I was just wondering if the Catholic Church was around in Kiltiernan back then as I believe the new one came into service in 1920.
To answer your question do I know these events happened in Sandyford Parish...well I’m not certain about the marriage but the births yes I’m certain as the birth records are available on the Irish genealogy website.
Anyway, thanks for the reply.