Today I received a new Ancestry DNA match to a previously contacted and determined by family history research to be a 3rd cousin.
I obviously missed out on this part of our mother's chromosome.
To add to this I also have my aunt's test results and she shares 175cM, 9 segments (unweighted 175cM, longest segment 38cM). 51% probability of being a 2C1R.
I'm confident with the combination of matches that our paper family history matches our DNA connection.
So if you have the opportunity to test other family members, do it now!
Excuse me now as I go to look at our shared matches to work out how they all fit in our family tree.