Hello Des, I cannot find a baptism for Sarah but there are 4 baptism records for this family (parents the same) in Lordship, yes a name of a parish, on the Cooley peninsula in Louth north east of Dundalk, from the parish registers site baptisms commenced in 1838 so I am assuming she was born prior to this . both marriages and baptisms commence in January 1838, see here https://registers.nli.ie/parishes/0191 Search by event and date then read page, can be difficult read.
On Roots Ireland a subscription site there are the following children, Matthew 6th October 1840, Cath 26th May 1838, John 25th Jan. 1843 and Patt in 1834 17th April.
Either the transcription is incorrect or Roots Ireland have accessed records that are not in our National Library and may be held locally but I searched 1830 to 1850.
Hanlon is a common name in the area, they were chieftains back in the day, McNamee less so. There is a good site for the Cooley area but an annual subscription is required, not a lot but it used to be free, mainly photos of families which were collected locally etc. See https://www.carlingfordpeople.ie/
Interesting site about Louth here also https://jbhall.clahs.ie/
Please revert if any further queries.
Regards
Pat