Note: "Constantine while still a young man, had married a lady called Helena. She was a daughter of the renowned Alypius, then the leading man in the city and member of a noble family held in high repute. This lady, who was not only beautiful but also virtuous, bore him three daughters before she died." 
Their three daughters were:
Eudokia. Eldest daughter. According to the Chronographia "in childhood she had been attacked by some infectious illness, and her looks had been marred ever since". She later became a nun.
At the time of their marriage Constantine VIII was the co-ruler of his older brother Basil II. Basil reigned as senior Byzantine Emperor from 976 to 1025 but never married. Which would make Helena the only Augusta during his reign. Constantine VIII would only become senior Emperor in 1025. Psellos does not mention if she was still alive by that point.
Ronald Wells, a modern genealogist, has suggested that Eudokia did not remain a nun for life. He has theorised an identification of Eudokia with the otherwise unnamed wife of Andronikos Doukas, a Paphlagonian nobleman who may have served as governor of the theme of Moesia. This theory would make Helena a maternal grandmother of Constantine X and John Doukas.
Wells has further suggested two daughters of the above proposed union. The first suggested daughter is Marija, the wife of Ivan Vladislav. The second daughter is "Sophia", an alleged wife of Manuel Erotikos Komnenos. Manuel was the father of Isaac I Komnenos and John Komnenos, the latter being the father of Alexios I Komnenos.
The theory apparently serves as a way to trace the ancestry of the Doukas and Komnenos families to the Macedonian dynasty. However if such a descent exists, primary sources are silent about it.
It shouldn't take two years to make an obvious decision on the merge: Given that Constantine VIII was born to a reigning emperor, you can safely stick with Porphrygenitos (however you want to spell it).
Van Byzantium-4 and Porphyrogennetos-4 are not ready to be merged because: I think there needs to be more discussion on what is the appropriate LNAB - Porphyrogennetos, is actually a title indicating that the person was born to an Emperor while he was reigning as Emperor and could be applied to any number of Byzantine dynasties. Van Byzantium doesn't follow the European Naming standards