Yet another OBS question

[NewCoach]

First my credentials: I am one of those that coach because if I didnt there wouldnt be a team. I played a bit of BB 30 yrs ago, but am new to fastpitch. I have read a few books, watch some videos, and go to as many games as I can get to so I can teach these 8Us (rec)some skills they can carry on to older age groups.
Yesterday we participated in our first scrimmage. The other coach, umpire, and myself agreed this should be primarily a learning experience for these girls, and a good time was had by all.
Now on to the question. BR hits the ball back to F1. F1 attempts to throw to F3. BR is in the basepath between F1&F3. The throw does not quite make it to F3 and get tangled in BR's feet. The umpire in training calls the runner safe. Almost immediatley the training umpire calls over the younger umpire, with me in very close earshot, and explains to her(and me) that that call should have been called runner interference, with the runner out because she didnt get out of the way for the fielder to catch the ball. I simply tried to learn from the trainer, but it seems from what Ive interperted from the rules the base runner has a priority, or generally superior right to the base path, and a ball thrown by a fielder that hits a runner is of no concern to the BR.
How should I coach these girls to run to first?

Thanks

[wadeintothem]

That play is live ball, play on.

There is no INT in that case.

How you teach your runners to run is up to you.

[Bretman]

Sight unseen, this might have been interference. By the written description, it probably wasn't.

Was the runner within the three foot running lane when contacted by the ball? If so (and she did nothing else intentional to interfere, like purposely kick the ball or reach out to swat it), then it is not interference.

If she was out of the lane, was the throw one that could have been reasonably fielded by the F3? If not (and it sounds like it was not, since it was bouncing in the dirt at the runner's feet) then that isn't interference, either.

Just being contacted by the ball isn't enough to warrant an automatic interference call. The runner must be both out of the running lane AND prevent the fielder from receiving the throw to be guilty of interference.