The 1881 Census, our prime source for John’s membership in the Stewart family, didn’t ask the “relationship to head of household” question, so we can’t be completely certain that John was in fact Daniel and Mary’s son and not, say, a nephew. Compounding that, Nova Scotia didn’t start civil registration of births until 1864. That said, he was born post-marriage, and moved with them to New Brunswick, so it’s a logical assumption.