Ric,
Tradition was to marry in the bride’s church which should be on the certificate, (unless it was a Registry Office marriage). That church may be the place to look for her baptism and that of any siblings.
You don’t say what denomination the 1861 ceremony. It was evidently Protestant. The local Church of Ireland (which is what the Young family appear to have been going by census records) lost its early records in the 1922 fire.
Looking at Griffiths Valuation for Tullyvannon in 1860, I see John Orr listed. He had plot 11 which was a 12 acre farm. There were only 16 farms in the townland and this was the only Orr property so pretty likely to be related to your Robert Orr, I would think.
http://www.askaboutireland.ie/griffith-valuation/index.xml?action=placeSearch
Robert Young is listed in Bockets on plot 30 which was a cottier’s holding of three quarters of an acre.
Looking at the revaluation records, which take Griffiths forward, I see that John Orr remains tenant in Tullyvannon till 1865 when he was replaced by Wm Blemins. Robert Young remains tenant on his property till 1897 when he was replaced by Robert McFarlane. Robert moved to plot 28 which was an 11 acres farm. (What you probably have there is Robert Young being replaced by another Robert Young at some point between 1860 and 1901. The clerks wouldn’t bother to delete a name only to write it back in again). If you get the younger Robert’s marriage cert, should give you his father’s name and occupation which Id expect to be Robert Young, farmer.
https://www.nidirect.gov.uk/services/searching-valuation-revision-books
1901 census:
http://www.census.nationalarchives.ie/pages/1901/Tyrone/Aghnahoe/Bockets/1734655/
1911:
http://www.census.nationalarchives.ie/pages/1911/Tyrone/Aghnahoe/Bockets/909121/
Probate abstracts:
Young Robert of Bockets Ballygawley county Tyrone old age pensioner died 1 January 1943 Administration Belfast 6 April to William Young farmer. Effects £170 7s. 3d.
Young, Mary (31) of Bockets Ballygawley county Tyrone married woman died 8 November 1959 Administration Londonderry 3 February to William Robert Young farmer the husband. Effects £104 8s. 4d.
Both were intestate and so there won’t be a will but you can find their next of kin from the probate file which is in PRONI in paper format.
So it looks as though there were Youngs in Bockets till at least 1959. Can’t help you with the Orr family though.
I searched the deaths for the Tullyvannon area c 1865 to see if John Orr had died. There is only 1 possible death around that time. He died 29.5.1869 aged 60. You might want to look at that cert to see if it’s your John Orr. You can view the original certificate on-line on the GRONI website, using the “search registrations” option:
https://geni.nidirect.gov.uk
You will need to open an account and buy some credits. It costs £2.50 (sterling) to a view a certificate.