I recently forced the creation of a DNA Circle at AncestryDNA by target testing a descendant of a common ancestor. This blog post offers some information about how I did it, and some of my reasoning for doing so.
AncestryDNA’s DNA Circles
AncestryDNA offers a tool called DNA Circles, which is a group of at least three individuals that share a common ancestor in their public family tree at Ancestry, and each member shares DNA identical-by-descent with at least one other person in the circle.
According to AncestryDNA, a DNA Circle “open[s] the possibility for AncestryDNA members to identify distant relatives with whom they do not share DNA IBD directly, but with whom they still have genetic evidence supporting their relationship.” Instead of relying on just triangulation, DNA Circles rely on the concept of a Genetic Network.