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I don't think we can determine who James married. Clonleigh is the only RC parish in Donegal with some records back to the late 1700s and you were lucky to find a baptismal record.
As you may know there is a sixty year gap for Clonleigh marriage records and they don't pick up until 1843. Here is a link to the parish register http://registers.nli.ie/parishes/0352
I have great-great grandparents from that parish ( Brennan/O'Donnell) so I'm familiar with the records available.