YOU SAID:
When will my parents be back
INTO JAPANESE
両親はいつ帰ってくるのか
BACK INTO ENGLISH
When will my parents come home?
INTO JAPANESE
両親はいつ帰ってきますか?
BACK INTO ENGLISH
When will my parents come back?
INTO JAPANESE
両親はいつ戻ってきますか?
BACK INTO ENGLISH
When will my parents come back?
That didn't even make that much sense in English.