Does the following sentence, mean the "ancestral communities" of A and B are exactly the same (bidirectional) or does it mean that only all "ancestral communities" of A are also "ancestral communities" of B, but B may have more "ancestral communities" (unidirectional)? If the structure is bidirectional, what other structure can I use to convey the unidirectional meaning?
If user A shares the same ancestral communities with user B, ...