The Nicholsons received grants of land in Sligo under the Acts of Settlement and one of them became High Sherrif of Sligo in 1671. In 1675 Edward Nicholson, described as of Cummin or Knocknaray, served as High Sheriff of Leitrim. The Nicholson estate extended in to the Barony of Leyny, covering part of the parish of Achonry. This estate was sold in the Landed Estates court in 1876 on behalf of Agnes Mary Nicholason, an infant. McTernan states that the Gethin family were the purchasers and they in turn leased it to several other parties. There were also legal proceedings within the family due to loans and mortgages. Two granddaughters of James Nicholson (d.1810), Emily and Harriett Douglas, were married to Adam Mossman and Thomas White, who also held land in Sligo. Adam Mossman was a Liverpool merchant. Various members of the Mossman family, who were married into the Nicholason family, held c.1000 acres in County Sligo in 1876. In November 1865 James C. Whyte Douglas offered lands at Luffertan, Woodpark and fishing rights at Culleenduff for sale in the Landed Estates Court. The original leases were between James Nicholson and the Earl of Erne's estate. George W. Douglas was still the owner of 70 acres at Culleenduff, in the 1870s.