My great great grandparents and my great grandparents lived in Killbeggan Parish.. HOWEVER, their marriages were performed in Delvin, Westmeath at the RC Church of the Assumption. I don't know why they would travel to the other side of the county...but they must of for a reason, unknown to me.
Here is a link to the Diocese of Meath website. You can see all the churches listed here:
Good Luck ! http://homepage.eircom.net/~meathdiocese/page6.html