I have located two graves for the Duck family at Lackan (Lacken) graveyard. You can find it on Google Maps by searching: Lackan Chapel & Graveyard, Lackan, Nolagh, Co. Westmeath, co-ordinates 53.63753, -7.42625). Lackan is a very small burial site, where part of the ruins of the Chapel still stands.
Based on Census records, this is the burial place of three of Daniel's brothers, Thomas (d.1970), John (d.1977) and Hugh (d.1979) along with his sister-in-law Elizabeth (d.1969) and Baby Stephen. There was also a burial in one of the plots just a year ago. I had been thinking of Multyfarnham, as KG suggested, but the death notice for the more recent death led me to Lackan. 1969/1970 are the earliest records on these headstones. It is quite possible that Daniel is buried here too. Also, there are a lot of old headstones whose inscriptions are not legible. I have submitted a query to the Parish of Multyfarnham to see if there is a record of Daniel's burial as I think Multyfarnham Parish also covers Leny/Leney and Lackan. I will post if I get a response.