Triangulating at 23andMe
After you sign in to 23andMe go to the left side of the page and follow the link to DNA relatives:
Select a relative of interest. I chose Patricia, a new “3rd cousin” match:
After you click or tap on the relative of interest, scroll down to “Find Relatives in Common.” Click or tap on the blue button:
Review the list of “Relatives in Common.” In this case, these are people who share DNA with me AND Patricia (shared matches). If there is “DNA Overlap” (neon green box) the shared match triangulates with me and Patricia. The work of triangulation is already done for me!
After the closest family members, the top relative in common who triangulates is a paternal first cousin once removed, Cousin “c”:
Additional triangulation along with some google searches and a message to Patricia confirm that Patricia is related to me through my paternal grandfather and now we know exactly how we are related!