Original:   The Maharajah of Travancore is therefore succeeded by his sister's son, and his own son receives a courtesy title but has no place in the line of succession.
Revised:  In Kerala, southern India, this custom is known as Marumakkathayam. It is practiced by the Nair nobility and royal families. The Maharajah of Travancore is therefore succeeded by his sister's son, and his own son receives a courtesy title but has no place in the line of succession.
Edit intent: coherence