Hi there - Records adre a lot scarcer for Catholics - they literally were second class folks at the time, so the land leases etc. don't help. I just checked the tithe applotment records, which was almost a head of household census when done - in the case of Clongesh it was 1825. There is only one Mallon there at the time - Charles Mallon in the townland of DEERPARK, which is adjacent to the demesne of Castle Forbes, on the north side. There were no Andersons there - and indeed Anderson is rare in Longford - only 6 listings , and all on the eastern side of the county. then in the Griffiths Valuation, there are three references to Thomas Mallon in Cloonellan Townland. It would be almost due west of Longford Town. There are no Andersons at all in Clongesh. A Margaret at Ballymahon, a couple in Longford Town. Still a rare name.
The Catholic Register in Newtownforbes does exist from 1829. Don't know where you are, but the Mormon Microfilm is #1279219 - it covers 1829 to 1881.
Except for possible Newspaper articles, that is about all I can think of.
