Yeah Dan turns out that Tiravera and Drumagelvin are not too far apart, however a quick look at townlands in between the two reveal more McKennas.
Here are all the Tehallan McKennas:http://titheapplotmentbooks.nationalarchives.ie/search/tab/r...
Use google maps - zoom to a particular level and townland names will be revealed, you then have to stay at that zoom level for the townland names to remain, searching will get you there also just beware spellings change alot between Tithe, Griffiths and google maps.
Anyway there are a few McKennas around the Condon and some are closer than Drumagelvin John, Tullylush/Tullylish is even about the same distance from Tiravera as is Drumagelvin.
Also Tiravera is right next to townlands in Donagh parish - havn't checked them yet but Donagh as a whole contains lots more mckennas than Tehallan parish.
Basically I'd prob need more info on Catherine ie Sibs, townlands, years etc, but also you yourself should look closely at all originals for townlands we've covered - check both in tithe and griffiths, also always look at adjacent townlands also.
Note also that if for example two adjacent townlands have both got a john condon then chances are its the same man with a couple of interests!
Usually - with mckennas in any case - if 2 men of same name in the same area then one will get nicknamed to make a distinkion (i know this spelling not rite)
So have a good study - you should also notice the same first names (mckennas) usually run in the family through the generations.
Any of this helping you dude or are you more confused, if more confused then mission accomplished - theres no end to it brother lol
Gabh raibh mile maith agat for the craic agus goodluck!