There were no McPaddens in Killinagh parish, Co. Cavan in Griffith's Valuation. I don't have any record of any McPadden births there.
I don't have any birth records (1864-71) with John and Catherine Flynn McPadden as parents. I would think that Mary Catherine McPadden and any siblings were born before that period. So the father, John, might well be old enough to appear in Griffith's Valuation (which was done in 1857 or before).
There are 2 John's in Griffith's, one being in Derrintawy Glebe (not very far from Dowra), the other in Mullaghcashel (close to Drumkeeran Town).