mariages between Hearne & Grant

[staffs]

My Great-grandmother Mary Herne born Portlaw circ 1840 gave birth to a daughter Mary born sept. 1868 Waterford.  The father was Michael Grant, but although she later refered to herself as 'The Widow Grant' before a later marriage, I haven't found any evidence of the first one.  I have however only found a marriage between Mary Hearne & a gentleman named Power.
Any ideas?
Staffs