@BzzBzz
are you refering to jap or english? because in english "in-law" is never used for adoptive relationships and would be a translation error if used this way. adoptive parent/mother/father is just adoptive parent/mother/father.
@LysandersTreason
kanji can have multiple pronunciations, but the meaning of the characters don't change because of it (usually). it's just a way for them to shoehorn stuff together to make it "cool" or add subtext to their word choice