There was also a Catherine M(a)cDonald, U.E. who was marred to a Hugh M(a)cPhee. Catherine was a daughter of John Roy M(a)cDonald, U.E.L. and Anne McDonell of Knoydart. I've only documented a marriage for their son Angus (married 1827 at St. Raphaels). This couple was also Catholic. This Catherine was likely a bit older than the Catherine from the first reply. This Catherine could have been born 1760 or earlier.
I know nothing more regarding Catherine (from my first reply)'s lineage. She is likely (from context) born closer to 1790-1800.