YOU SAID:

The mother-in-law called yesterday and we have to cook.

INTO JAPANESE

昨日、義母が電話して、料理をしなければなりません。

BACK INTO ENGLISH

Yesterday my mother-in-law had to call and cook.

INTO JAPANESE

昨日、私の義母は電話して料理をしなければなりませんでした。

BACK INTO ENGLISH

Yesterday my mother-in-law had to call and cook.