Katelyn,
What?s the church name and denomination that the marriage took place in? (Tradition was generally to marry in the bride?s church, and hence my curiosity). I suspect it was Irvinestown RC. Is that right?).
I think the address for the Leonard family may be Baragh, which is a townland near Ballinamallard and in the RC parish of Irvinestown. The modern Baragh Rd runs through it. I searched Griffiths Valuation for Baragh to see if there was any Leonard household listed there in the 1860s. There is not. However that doesn?t mean the family didn?t live there. It just means that either they were lodging with someone else or they had a cabin of too low a value to merit including in Griffiths.
No Leonards in Baragh in the 1901 census. However I did notice 4 shoemaking Leonard households in the county. A trade like shoemaking often ran in families, so some of these might be relations:
http://www.census.nationalarchives.ie/pages/1901/Fermanagh/Churchill/Aghamellan/1360409/
http://www.census.nationalarchives.ie/pages/1901/Fermanagh/Rahalton/Derrygormelly/1363370/
http://www.census.nationalarchives.ie/pages/1901/Fermanagh/Enniskillen_Urban/Queen/1364714/
http://www.census.nationalarchives.ie/pages/1901/Fermanagh/Castle_Coole/Garvery/1363860/
For the households where the head is a widow, you would probably need to try and find the births of the children (post 1864) on the GRONI site, to see if any had Leslie L as the father.
There?s a death for a Leslie Leonard that looks encouraging. Died 28.12.1894, death registered in Irvinestown. Estimated year of birth 1810. You might want to view a copy of that. (If it shows a different townland for his death let me know). Also worth noting the identity, address and relationship of the informant.
With the other townland (ie the Mills address), if it was a different parish, and especially a different county, the Minister would often put that eg ?Ballygobackwards, Parish of Puckoon.? If it was a local townland, then they just put the townland name. So I?d expect the townland to be near the church. One possibility is Aughey but again I can?t trace the Mills family in the relevant records.
I assume this is your James & Elizabeth in 1901 &1911 (I note they had just 1 child, who was still alive in 1911):
http://www.census.nationalarchives.ie/pages/1901/Fermanagh/Brookhill/Letter/1353691/
http://www.census.nationalarchives.ie/pages/1911/Fermanagh/Brookhill/Brookhill/519766/
The revaluation records show James arriving in Letter in 1889. He had a house and outbuildings on plot 3 (which was a farm owned by the Irvine family). So that points to him having a fairly low value property. It had a rental value of ?3 10/- a year so was lucky to be in Griffiths. The records indicate he left in 1906 (presumably to Brookhill).
Elwyn