YOU SAID:

i smashed my sister in laws window

INTO JAPANESE

私は義理の窓で妹を壊した

BACK INTO ENGLISH

I smashed my sister at my stepsister's window

INTO JAPANESE

義理の妹の窓際で妹を殴った

BACK INTO ENGLISH

I beat my sister-in-law by her window

INTO JAPANESE

私は義理の妹を窓際で殴りました

BACK INTO ENGLISH

I hit my sister-in-law by the window

INTO JAPANESE

窓際で義姉を殴った

BACK INTO ENGLISH

I hit my sister-in-law by the window