I'm wondering how to use information derived solely by DNA testing when compiling a family tree.
My apologies in advance if the example below is a little complicated.
I know that I (say person A) am related at third cousin level with person B. We have both done DNA testing and on shared DNA matches we have a common 4th cousin (say person C). C has other close relatives with whom we also share DNA (also shown as 4th cousins to A and B).
Person C is totally unknown to A and B and have no shared surnames. Person C's tree goes back to about the same time period as the shared ancestor of A and B (born 1830's) and we have no idea of any ancestors prior to that.
It must be that a marriage occurred sometime early to mid 1800's which connected the respective families. I have found one such marriage on church records which could be the link but at this remove I don't see any easy way of finding conclusive proof.
My question basically is: would you rely on DNA evidence to build an extended family tree when there are no other means of proving the exact relationship? If so, how would you represent them in the family tree.