I searched the Irish Family History Foundation's database. It contains 11,500,000 surviving rcds for abt 60% of Irish counties. Co. Roscommon rcds are in it. All Irish rcds B4 1840 are sparse.
For Patrick McCormick (+variants) M 1861 (exact) in Co. in Ballinameen parish, Roscommon, I found 2 M rcds; these may be duplicates. For Catherine Keenan using the same search, I found 2 M rcds.
For Luke Morrisroe (+variants) M 1860 (exact) in Co. Roscommon, Ballinameen parish, I found 2 M rcds. For Winifred Farrell, I found 2 M rcds.
Suggest you google the Foundation's name. This will lead you to the database. A view of the detailed rcd for each marriage SHOULD list the names of the parents of the couple. It may also show their ages. Armed with that info, you can search for their B rcds.