YOU SAID:

I have a mother who has a father who has 2 mothers

INTO JAPANESE

私には2人の母親を持つ父親を持つ母親がいます

BACK INTO ENGLISH

I have a mother with a father who has two mothers

INTO JAPANESE

私には2人の母親を持つ父親を持つ母親がいます

BACK INTO ENGLISH

I have a mother with a father who has two mothers