Why have you discounted the marriage between Thomas H and Ann Bennet? They married in 1743 in Andover and there are a series of baptisms in Andover to a Thomas and Ann Hopgood,
Ann 1745, Mary 1747, Thomas 1748, John 1752, John (again) 1761 and Sarah 1761 (same date as John #2). John #2 may have been baptised later than typical rather than a twin to Sarah.