Complex sentence: He and Philomena spent years researching, until they discovered that her son had been put up for adoption by the nuns at the Abbey, and adopted by an American couple, Doc and Marge Hess, and had been named Michael Hess.
Split into simpler sentences: He and Philomena spent years researching, until they discovered that her son had been put up for adoption by the nuns at the Abbey. He was taken by an American couple, Doc and Marge Hess, and named Michael Hess.