Daniel and Cassandra Bettencourt of Wellesley announce the birth of a son, Nash Grant Bettencourt, born March 24 at Newton-Wellesley Hospital. Nash weighed 9 pounds, 6 ounces at birth. His proud grandparents are Susan and Peter Bettencourt of Edgartown and Paul and Kathleen Severino of Concord and Oak Bluffs.