YOU SAID:

My mother is fighting my mother in law about the flying lion

INTO JAPANESE

空飛ぶライオンのことで母が義理の母と喧嘩している

BACK INTO ENGLISH

My mother is arguing with her mother-in-law about flying lions.

INTO JAPANESE

私の母は義理の母と空飛ぶライオンについて口論しています。

BACK INTO ENGLISH

My mother is arguing with her mother-in-law about flying lions.