Hi Betty,
All Robert and Mary's children appear to be born in Rathdown registration district (R.D.) of Wicklow. The one's we know of from the censuses and FamilySearch baptisms:
- John, b. 15 Jun 1878
- Mary, b. 13 Aug 1880
- Margaret, b. 1884
- Thomas, b. 1886
- Catherine, b. 1891
- Sarah, b. 1896
- Ellen, b. 1898
- Hilda Maria, b. 11 Oct 1900
We know they had twelve children, eight of whom were still living in 1911 (5 at home, leaving 3 out in the world somewhere). John is probably this fellow -
http://www.census.nationalarchives.ie/pages/1911/Wicklow/Bray_No__2/Sidmonton_Avenue/892109/ - living with his wife Ellen Mary (née Coe), who he married in 1904 in Rathdown R.D.
The four remaining children are likely to have died young. I've been through the births and deaths registered in Rathdown district between 1877 (the year of Robert & Mary's marriage) and 1901 and found a few possibilities for their missing children:
- 'Male', b. 1878, d. 1878
- Agnes, b. 1879, d. 1879
- Philomena, b. 1879, d. 1885
- Ellen, b. 1881, d. 1881
- John James, b. 1887, d. 1887
- William, b. 1889, d. 1894
- Alfred Leo, b. 1888, d. 1888
- James, b. 1891, d. 1892
- William Joseph, b. 1894, d. 1894
Given the 'Male' Boyd and James Boyd were born the same years as known children of Robert and Mary, we can rule those out, leaving seven possibilities. Unfortunately, I can't whittle the list down any further from just the civil indices, so unless you purchase the certificates it's unlikely you'll know for sure which kids belong to your couple.
FYI, there's a Robert Boyd d. 1923 aged 61 registered in Rathdown, putting his birth c.1862 - a little out for your Robert, but that's not uncommon. Similarly, there's a Mary Boyd, d. 1919 aged 53 (b. c.1866), which may be his wife.
T