Robert Kerr & Margaret Robinson were also my GGG grandparents. Over the years we have found considerable information about their descendents, many of whom are posted on my web site(
http://home.primus.ca/~lstitt/geneal.htm). TMCLELLAN is more closely related than you and I are.
It is possible that my mother has spoken with your mother or grandmother. I remember our visiting someone in the area to gather some genealogical information.