I searched the Irish Family History Foundation's database. It contains 12,000,000 surviving rcds for abt 65% of Irish counties. Cnty Meath rcds were just added to it. Cnty Mayo rcds are also in it.
For Mary Maguire B 1864 (exact) in Meath, I found 17 B rcds. For the parish of Summerhill, I found 0 B rcds.
For Frederick Picking M any date in Co. Meath, I found 0 M rcds.
B/M/D registration was civil beginning in 1864. The civil rcds are kept by the General Register Office. Contact it at http://www.groireland.iehttp://www.groireland.ie.
For John Maguire M 1859 +/- 4 yrs, I found 3 M rcds. For Catherine Ging M ditto, I found 0 M rcds. The closest is in 1852. The Ging surname shows nearly 3,000 B rcds, most in Cntys Antrim, Down, Tyrone, and Armagh. Only 38 were in Meath.
Google the Foundation's name to lead you to this database. I think you will like it. Best of luck. Pls post your search results to this genforum message.