Assertion: niece's mother | /r/HasProperty | sister
Facets:
Source sentences:
text: Likewise, their sons were also half-brothers (between them and with their mothers), having the same father, as well as cousins, having mothers that were sisters.
text: James is Jack’s matrilateral ortho-cousin (related through Jack’s mother Felicia and Felicia’s sister Georgina).
text: Also, I have a cousin called Anna - our mothers are sisters