A couple more queries:
1. I have a copy of a will written by John Dawson, merchant of Castle Street Dublin. The will (proved 7th February 1801) refers to sons Alexander Dawson and James Dawson, daughters Catherine Henry and Margaret Beahan, and his sister Mary Barnside.
Is this family connected to the Dawson's of Castledawson?
2. Alexander Henry married Catherine Dawson on 29th March 1792; his will is dated 1796.
Have you any information about Alexander? To date I cannot find any reference to Alexander among the Kildare & Dublin Henrys and wonder if instead he was a member of the Castledawson branch.