Information from previous topics
Based on the census returns, your family lore and searches here to date I have deduced the following, subject to confirmation:
William Boothman (Father John and Mother Mary)
b. c1861 d. ?? Oct-Dec 1931 Rathdown V2 P489
married in Jul-Sep 1886 Rathdown V2 P771 in Kingstown RC Church (Dun Laoghaire)
Sarah Sheridan (Father Patrick and Mother Anne)
b. c1865 d. ?? Apr-Jun 1903 Dublin South V2 P567
Parents names from Church Records
Civil reference Jul-Sep 1886 Rathdown V2 P771
There is a reference to Sarah in 1899 that states she was born in Newtown Park
There is a baptism in Blackrock in 1865 (Father Patrick and Mother Anne) that may be her
I cannot locate William’s birth
Births
Anne: Jan-Mar 1888 Rathdown V2 P867; baptism Kingstown 1887
Possible marriage in Oct-Dec 1911 Rathdown V2 P913
Match is one of John O’Dea, Patrick Traynor, George Henry McMahon or William Matthews
Mary: no obvious civil record; baptism Kingstown 1890
Possible death in 1954 unmarried
Patrick: Apr-Jun 1893 Rathdown V2 P833; baptism Kingstown 1893 as BOOTMAN
Possible marriage in Oct-Dec 1928 Rathdown V2 P407
Match is one of Bridget Burke, Mary Carlon, Katherine McMahon or Josephine O’Brien
John: no obvious civil record; baptism Kingstown 1895; died Jan-Mar 1932 Rathdown V2 P579
Married Christina Traynor in 1927;
They had a daughter Mary in Jan-Mar 1931 V2 659 that married in Dorset, UK
Sarah Philomena younger sister to Mary??
Christina Traynor-Boothman married James Dalton in Jan-Mar 1935 Rathdown V2 P570
They had a son in 1936
Sarah: Jan-Mar 1898 Rathdown V2 P852; baptism Glasthule 1897 as BOOTMAN
no further obvious records
Rosanna: Apr-Jun 1901 V2 P803; no baptism online
Possible marriage in Oct-Dec 1920 Rathdown V2 P850
Match is one of John Hynes, Thomas Handy, John Neligan or William Molloy
There is an 1903 birth & death of a William Boothman in Dublin South which could be a further member of the family especially in light of the possible death recorded on-line of Sarah in the same year. William declared himself a widower in 1911 so this record, although the age is slightly out, is probably correct.
Could Sarah Philomena Boothman have been adopted?? or a family member taken in as their own?
It wouldn't answer why her birth wasn't registered unless it was as another name and she assumed Boothman.
Using her sister's birthdate could have come about if she required a birth cert or formal ID for something and used it instead of her own.
My last suggestion for today is to contact the church where Mary Boothman was baptised in 1931 and see if there are any other records there in the years from 1927 to 1935 (date of first marriage to second marriage) for other siblings
