Related על קידושין 4:4

A female Levite or female Yisrael—[one who seeks to marry them should] add upon them an additional one [generation on both sides that he should investigate to understand their lineage, 1 more than for a female Kohen], which is 12 [people to investigate]. (The following translated from the Ehrfurt manuscript:) If he investigated the mother, he does not need to investigate the children. If he investigated the adults, he does not need to investigate the minors. When does this apply? When [investigating a family that has] one wife. But when [the family has] 2 wives—if he investigated the mother, he needs to investigate the children; and if he investigated the adults, he needs to investigate the minors [because they might be born from different women].