There are 26 pieces of land leased by Ferguson's between 1820-1839. None named Meredith or Duke.www.genealogy.nationalarchives.ie
Griffith Valuation is the next census substitute dated 1857
52 lands in lease to Ferguson's. 6 of which are in Ballysadare Parish. 2 named John, 3 Edward, 1 Martin
There are also Meredith's 20 as well.www.askaboutireland.ie
Most counties in Ireland belong to an Irish History Foundation an online not for profit but fee paying. However, the Parish of Ballysadare has no records
for baptisms or marriages for Cathlics. Church of Ireland has records from 1842-1899 for baptisms and
marriages from 1858-1899.
Not sure why but its possible they are in local custody of the parish or that the Church of Ireland recorded baptisms and marriages as the Establish Church of that time.
Try the 'Registery of Deeds - Ireland' as see if there is anything there.