You could have changed it as long as you had definite knowlege that you called the wrong line.
Now, some in here are going debate up to what point you could have corrected it.
- A) Up until the moment B1 had ball at her disposal for throw-in
- B) Up until the time B1 released the ball on her throw-in
- C) Up until the time the throw-in ends
I personally would go with
C.