Charities: A Will & Two Ways

The southern tip of Texas is a desolate land—flat, sandy, baked the year round by a relentless sun. Ranches here are measured in thousands of acres, and some of the sprawling estates rest on an unexplored ocean of oil. It is over one such pool of wealth that two rival groups of Roman Catholics have been waging a bitter battle of words and wits that echoes all the way to the Vatican.

At stake is the fortune—which may prove to be worth as much as $300 million—left by the late Sarita Kenedy East. She was a granddaughter of Captain Mifflin...