My g-g-grandfather, Joseph Augustin Giroir, and my g-g-grandmother, Elizabeth Montet, were distantly related, which meant they had to seek the Catholic Church’s permission to marry. There were varying degrees of dispensations. In their case, Elizabeth’s grandmother and Augustin’s grandfather were brother and sister.
Apparently dispensations were very common among the first several generations of Cajuns.
Some of the requests can be found at http://archives.nd.edu/mano/default.htm#Al Someone has even kindly summarized what’s contained in handwritten documents.
A veritable trove!