YOU SAID:
i ate breakfast with my sister-in-law
INTO JAPANESE
私は義理の妹と朝食を食べました
BACK INTO ENGLISH
I ate breakfast with my sister-in-law.
INTO JAPANESE
朝食は義理の妹と食べました。
BACK INTO ENGLISH
I ate breakfast with my sister-in-law.
That didn't even make that much sense in English.