You answered the knock knock question with another question...
If the phone rings, do you answer the phone and ask "who's there?" Maybe you do, but that's not the usual response.
I asked a question with knock, knock? You're supposed to answer, not ask a question.
Let's try again. Knock knock?
What is your answer?
BTW, I just rethought this. I told you, it's really, really hard!
2nd weighing is 4x4 as well!
!st weighing is 4x4
2nd weighing is 4x4
3rd weighing is 1x1
This is now 100% absolutely correct! I know it doesn't matter to you, but I wanted to correct my hints.