I have been surfing the net for Merlehan connections. I came across a reference in the 1911 Census for Ireland to the residents of a house in Janeville Cottages (North Dock, Dublin), who would appear, from the names you have given, to be the family you are looking for.
My Merlehan connections are my gggrandparents Charles Merlehan who married Catherine O'Reilly in Westmeath in 1854 before sailing to Queensland, Australia in 1855 on the ship,the Cambodia. Charles parents were given as John and Mary Merlehan of Westmeath and Catherine's parents were Edward and Anne O'Reilly of Westmeath. I think that there may be a connection to the townland of Clonmaskill.