I actually would not know how to start to answer your question. It seems more of a statement that you have sent a private message to someone whose name includes 'McKinnon'. It seems that in your message you have asked McKinnon about two ladies, Martha Durr and Mary Ann Todd.
Hopefully McKinnon already knows who you are talking about or what part of the world or section of time they are connected with.
For those of us on this G2G forum who would like to help you with your question, the best starting point would be a link to the profiles of each lady. If there aren't profiles yet, then the question would need to include all known info and some indications of the research that has already been done that came up blank.
We would need that because there are a lot of people in lots of parts of the world that were named Martha Durr (88 with that or similar name already have profiles here at WikiTree) and even more named Mary Ann Todd (6,189 profiles here with that or similar name).
We would like to help. We just need a starting point.
Cheers
Shirlea