I am not familiar with this family. However I was wondering whether you had looked in the Registry of Deeds for any information on him or his family?
a Merchant of Ballinrobe
he or his family might have used the Registry, which commenced from 1708. If you are really lucky you might even find a marriage settlement. Nick Reddan’s Registry of Deeds Index Project has provided a partial index to this collection and is available at http://www.irishdeedsindex.net That website provides some useful guides to the Registry of Deeds also.