Gronwy's father showing as dying "after circa 1086". I looked at a chart in Wolcott link who pegs the birth at 1090: http://www.ancientwalesstudies.org/id55.html
I don't know the original reasoning in assigning "after circa 1086" for the father. If there wasn't a firm rationale, perhaps changing the father's death year to "after circa 1090" might be valid.
