Armstrong family cavan/ meath

[marykins]

hi
   iam looking for any information on the family name of Armstrong from around the Cavan / Meath area.
my grandmother was Katie Armstong  and was Daughter of William Armstrong & Catherine Brennon.

 Katie Armstrong marred Peter Geraghty on the 23 Oct 1904 in the RC church in Oldcastle.
peter & katie both from the fennor area of Oldcastle.

 going off the 1901 census peter Geraghty was the son of Margaret Connelly.
 peter Geraghty aged 30 was b 1871. his mother Margaret Connelly was aged 60 (widow ).

this is all the infomation i have on my grandperants so far.
my family seemed to have lived all there lives down in the fennor area of oldcastle.
this family have a very strong connetion to the Masterson family also of that area.

this area is very confusing as it is on the border of co Cavan & Meath.

any help finding pointers to how find anymore info would be grateful......