OBS or nothing

[DaveASA/FED]

BR hits the ball to the area between 1st and 2nd, 1st goes after it, 2nd coming over to back up both are heading to bag, 2nd pulls up to let 1st run and touch the bag herself, BR is coming down the line in running lane (ASA) toward the orange bag, 1st runs through the base sideways touching the white portion then overruns the orange to end up on foul territory. I call the out as she is there prior to the runner. Runner pulls up slightly as she is a couple of steps from 1st seeing the player running perpendicular to her. 3rd base coach asks about OBS as the runner slowed down due to the fielders action. I stated that the fielder had possession of the ball so there was no OBS.

1) Is this correct?
2) what if 2nd would have continued to run to first and the runner would have reacted to the actions of the 2nd baseperson? how would you determine she reacted to the 2nd baseperson not the 1st with the ball??