I search the IFHF's online database at ROOTSIRELAND.IE. It has abt 20 M church/civil/census B/M/D records for MOST Irish counties. Records are increasingly sparse before 1863 and almost non-existant before 1800.
For a Mary Degnan and Roger Tighe marriage in 1858 +/- 5 yrs, somewhere in Ireland, with the parents' names unknown, I found 1 record: 1855, Co. Roscommon.
For Thomas Tighe B 1860 +/- 2 yrs, Co. Roscommon, with a father forenamed Ro(ger/Robert), and mother Mary Degnan, I found 1 record in 1858.
For a Ce(cillia) Tighe B 1861 +/- 10 yrs, somewhere in Ireland ditto, I found 1 record: 1856, Co Roscommon.
For Michael Tighe ditto, ditto, I found 1 rcd: 1861, Co. Roscommon. The parents' forenames are listed as "R" and Mary. The mother's surname may not have been recorded.
For Roger Tighe B 1864 +/- 4 yrs, somewhere in Ireland with the ditto parents' names, I found 1 record: 1864, Co. Roscommon.
Using the IRISHGENEALOGY.IE database, I searched for Agnes McCann B 1866, Dublin (City) records. I found 1 record: 20 Jan 1866. Parents names are listed as Mathoi McCann and Mariae Dowling. The address is Charlemont Street, Rathmines (parish), Dublin.
The above look like direct hits on your ancestors. Suggest you visit the databases (some have small fees) and view the detailed records for their exact DOB, and other info.