Rundown and OBS

[DaveASA/FED]

My question is when does the OBS protection stop? Once the play is over? Or once the player has reached the base they would have made had there been no OBS? I remember reading almost those exact words in the book, sorry at work and book at home I will look up later.

So if BR hits a ball to shallow center field and rounds 1st into stupid F3 I have OBS, F8 throws back to F6 so R1 (former BR) retreats to 1st base (the base she would have gotten with no OBS) then there is an overthrow to F1 and R1 takes off for 2nd, you are going to protect R1 between 1st and 2nd? If thrown out put her back on 1st?