YOU SAID:

my dad got milk and is not back yet

INTO JAPANESE

私の父は牛乳を飲んでいて、まだ戻っていません

BACK INTO ENGLISH

My dad is drinking milk and hasn't returned yet

INTO JAPANESE

私の父はミルクを飲んでいて、まだ戻っていません

BACK INTO ENGLISH

My dad is drinking milk and hasn't returned yet