- James R. Hope Scott bought lands in the parish of Ballintober, barony of Carra and in the parish of Addergoole, barony of Tirawley, county Mayo, from the 3rd Marquess of Sligo in the mid 1850s. His representatives owned 2462 acres in county Mayo in 1876. In 1887 the second daughter of James Robert Hope Scott married Nicholas Robert O'Conor, a member of the O'Conor family of Dundermott.
- Port became part of the Peyton estate through the marriage of John Hamilton Peyton to Mary Cunningham, heiress of Port, in 1814. John Hamilton Peyton of Port was High Sheriff of Leitrim and in 1851 was a member of the Grand Jury for Leitrim. In the mid 1850s the house at Port was occupied by George Latimer. The Port estate, 726 acres, was advertised for sale in the Encumbered Estates' Court on 28 June 1853. Included in the sale was the townland of Ballyglass South, 555 acres in the parish of Kilcroan, barony of Ballymoe, county Galway. This townland was in the possession of Patrick O'Connor, who had purchased it at the Encumbered Estates Court sale, at the time of Griffith's Valuation. The Freeman's Journal gives details of the purchasers of the county Leitrim property. In January 1865, property in county Leitrim owned by Anna Cunningham was sold in the Landed Estates Court. Charles W. Peyton was the petitioner to the sale and one lot was purchased in trust for him while the second lot was purchased on behalf of the Earl of Leitrim.
- A branch of the O'Conor Don family who resided at Dundermot for 2 generations in the 19th century. In 1683 Hugh O'Connor was granted over 1,800 acres in county Roscommon, including the castle of Ballyntobber and lands at Laraha and Ross. At the time of Griffith's Valuation, Patrick O'Conor held land in the parishes of Kilcroan and Kilbegnet, barony of Ballymoe, county Galway, and in the parishes of Oran and Drumatemple, barony of Ballymoe, Lissonuffy, barony of Roscommon, county Roscommon. Some of this land was held from the Blakeneys and some of the land in the parish of Oran was offered for sale by the Brownes of Castlemagarrett, county Mayo in May 1852. His brother Roderic also held land in the parishes of Oran and Drumatemple. In 1851 some of Roderick O'Connor's land in the parish of Drumatemple was advertised for sale in the Encumbered Estates' Court by his assignee Christopher Hume Lawder. From 1853 Patrick O'Conor held Laragh and Ross, which adjoined the demesne of Dundermot, from Arthur Irwin Mahon. Mahon advertised these lands for sale in May 1856. Patrick O'Connor and Charles O'Connor also held extensive lands at Rathconor and Tonlegee, parish of Kilbride, barony of Ballintober South at the time of Griffith's Valuation, previously part of the Croghan estate. In the 1870s Hussey records that the late Patrick Hugh O'Conor of Dundermot owned 2,435 acres in county Roscommon and his brother Nicholas O'Conor owned 810 acres. Nicholas O'Conor, a prominent British diplomat, sold Dundermot. The estate of his daughter Fearga O'Conor was vested in the Congested Districts' Board in March 1915.
- The O'Conors of Milltown, barony of Castlereagh, county Roscommon, share a common ancestry with the O'Conors of Dundermott and appear to have been resident at Milltown from the mid 18th century. Gormley states that the O'Conors acquired this estate on the death of Gerald Dillon of Dillon's Grove who had been granted it and whose daughter Mary had married Thomas O'Conor. The Milltown branch held lands in the parish of Kilcroan, barony of Ballymoe, county Galway, in the mid 1850s. Roderick O'Conor was one of the principal lessors in the parish of Kiltullagh, barony of Castlereagh at the time of Griffith's Valuation. In the 1870s Roderick Joseph O'Conor of Milltown, Tulsk, county Roscommon, owned 384 acres in county Galway and 1,496 acres in county Roscommon. In 1909 the O'Conors were negotiating with the Congested Districts' Board for the sale of almost 2,000 acres of their estate in counties Roscommon and Galway.
- The Mahons of Cavetown, county Roscommon, were descended from Peter Mahon, the fourth son of Nicholas Mahon of Strokestown. Peter became Dean of Elphin in 1722. This family also had property at Templeoge, county Dublin. By 1830 when the estate was put up for sale it was comprised of the lands of Laragh and Ross in fee, Crieve held from the See of Elphin and Cavetown held on a lease for 3 lives renewable for ever. Cavetown was in the possession of Guy Lloyd of Croghan by the late 1830s. Arthur Irwin Mahon advertised for sale the lands of Laragh and Ross in May 1856. The 737 acres were all held by Patrick O'Connor on a lease from Arthur I. Mahon for 3 lives or 61 years, dated 3rd March 1853. The lands adjoined the demesne of Dundermot, residence of Patrick O'Connor.
- In 1749 Charles Croghan and Luke Croghan were both resident in the parish of Kilbride and Owen Croghan in the parish of Boyle. In 1778 a Croghan residence is marked on the Taylor and Skinner map at Ardmore, parish of Dunamon, barony of Ballymoe, county Roscommon. In the mid 19th century the Croghans held land from the Earl of Essex in the parish of Kilbride, barony of Ballintober South, county Roscommon. The rental of the lands of Tonlegee, Rathconor and Smaghraan, held under a fee farm grant dated 26 June 1851 from the Earl to Elizabeth Croghan, was advertised for sale by James Croghan a minor and heir of Edward Croghan and Christopher Hume Lawder assignee of Charles Croghan, deceased. These lands amounting to 1,958 acres were in the possession of Patrick and Charles O'Conor and William McLoughlin at the time of Griffith's Valuation.