Keep in mind that adoption was not legislated in Ontario until 1921. As such children were often placed with friends or relatives and their names were simply changed.
Aaron Bear died in 1870 leaving a widow and four young children. There seems to be confusion between another Aaron Bear and another Barbara Martin. According to the Eby book, they lived in Doon. If they were farmers, Barbara possibly lost the farm when Aaron died (or would have at least had difficulty maintaining it). Aaron is buried in Hagey Cemetery (A-12-1).