Complex sentence: They had eight children, including Countess Jimena Peláez married to Count Vermudo Ovéquiz and parents of the powerful Count Suero Vermúdez.
Split into simpler sentences: They had eight children, including Countess Jimena Peláez who was the wife of Count Vermudo Ovéquiz. They were parents of the powerful Count Suero Vermúdez.