YOU SAID:
I just found grandma in the park
INTO JAPANESE
私はちょうど公園でおばあちゃんを見つけました
BACK INTO ENGLISH
I just found my grandma in the park
INTO JAPANESE
私はちょうど公園で私のおばあちゃんを見つけました
BACK INTO ENGLISH
I just found my grandma in the park
That didn't even make that much sense in English.