The Presbyterian Historical Society in Belfast should have details of the Rev Winslow’s career as a Minister. That information often contains details of his birth, where he obtained his degree (Usually in Scotland), where he served as a Minister and sometimes details of his wife and family.
http://www.presbyterianhistoryireland.com
There are 2 Presbyterian churches in Donagheady. Donagheady 1st only has records from 1875 and the 2nd from 1838. So there don’t appear to be any records for the 1700s when the Gibson children were born, assuming they were baptised in one of those churches. If, by chance, the Gibson family was Church of Ireland, then their Donagheady records are:
Baptisms, 1697-1723, 1753-65, 1818-19 and 1826-74;
marriages, 1697-1726, 1754-64 and 1826-44; marriage
licences, 1817 and 1829-53; burials, 1698-1726, 1754-
7 and 1826-89; vestry minutes, 1697-1723 and 1754-
1919; accounts, 1829-1922; confirmation lists, 1872,
1875, 1877, 1880, 1883 and 1886.
I do not know if this is your family but I noticed this death notice in the Londonderry Sentinel for 14th Sept 1833: “On Sunday last, the 8th inst., at the house of his daughter, Mrs. Cowan, of Strabane, Mr. Joseph Gibson, at the advanced age of 84 years”.
