Gilmore family

What ages were the children?

It looks like they were born almost immediately prior to leaving Ireland. They left in 1889 and the census indicates they were born in 1887 and 1889. Of course, the son's obituary in 1918 says he was 32. So I am not quite sure. I'm in Belfast now. The only Rose Ann Gilmore in the birth indexes is from Belfast. But parish records aren't available-assuming I knew the parish. 

Civil registration of birth? Possible? Useful?

it looks like the older Patrick's brother John emigrated in 1890. He then disappears.

It looks like they were born almost immediately prior to leaving Ireland. They left in 1889 and the census indicates they were born in 1887 and 1889. Of course, the son's obituary in 1918 says he was 32. So I am not quite sure. I'm in Belfast now. The only Rose Ann Gilmore in the birth indexes is from Belfast. But parish records aren't available-assuming I knew the parish. 

Civil registration of birth? Possible? Useful?

it looks like the older Patrick's brother John emigrated in 1890. He then disappears.

The civil indexes list births for Patrick Gilmore in Newtownards in 1885, & 1886; Belfast 1886; Antrim town 1886; Newry 1885; Ballymena 1885; Downpatrick 1888 & Kilkeel 1888. (These are all in either Co Antrim or Co Down).

There are no Rosa births but for Rose, widening the search from 1886 to 1892 and for all Ireland, there are just 3 births, in: Belfast 1886 and, as you say, Rose Ann in 1890 and another Rose Ann in Kilkeel in 1886. The problem with the Belfast Rose Ann is I think she stayed in Belfast. This looks to be her and her family in the 1901  & 1911 censuses:

http://www.census.nationalarchives.ie/pages/1901/Antrim/Smithfield/Galway_Street/973379/

http://www.census.nationalarchives.ie/pages/1911/Antrim/Smithfield/Pound_Street__file_2_/186765/

I have looked on Emerald Ancestors index for a Patrick Gilmore marrying a Mary in Co Antrim or Down. The only matches are 1877 in Ballymena (to Mary Anne) and 1891 in Antrim town, and 1894 Belfast (both to Mary). So too early or too late.

The cheapest way of looking at all the births would be to go to GRONI in Chichester St, Belfast and pay for a days searching which costs ?14. (Booking is advisable. Ask for an index search).  You get to look at all the indexes for births, deaths & marriages in Northern Ireland. It includes two free readovers (ie you get to see the certificate and can transcribe the details). Extra readovers are ?4 each. Hopefully just one Patrick and one Rose will have parents Patrick & Mary. I?d probably start with the 2 Kilkeel births.

http://www.nidirect.gov.uk/gro