Hi Sarah
Your next step will be to search the 'big' Irish databases such as Irishgenealogy.ie and Rootsireland.ie for marriage record of James Bloomer to Isabella and John Siberry to Mary. A 'civil marriage' record, if found, will identify the names of fathers of both bride and groom.
RootsIreland index, for example, records marriage of a James Bloomer to Isabella in County Tyrone in 1891. This marriage certificate can then be viewed and downloaded at irishgenealogy.ie (
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1891/10666/5886547.pdf), which shows that James Bloomer of Creevelough (Aghaloo Parish, Tyrone), son of Thomas, married on 11 June 1891 in Parish Church of Brantry, County Tyrone, Isabella Stewart of Ballyvaddy (Aghaloo parish, Tyrone), daughter of Henry.
Now part of united parish of Killylea, Caledon and Brantry you can view a photograph of Brantry Church of Ireland church at
http://armagh.anglican.org/Parishes/KillyleaCaledonBrantry.html