Charles I of Naples
Gordon McDaniel proposed that Maria's husband Anselm "de Chau", who was Captain General in Albania (1273–1274) for Charles I of Naples, was the same person as Anselm ""de Keu", who was mentioned in 1253–1254 as husband of Maria, daughter of John Angelos of Syrmia. According to McDaniel, Maria and her sister Helen were descended, through their father John, from a side branch of the Byzantine emperor's family, and the Hungarian royal house.