Batter Runner Interference or not
 

What would the ruling be in softball on this play (see play from Astro's vs White Sox for a visual).

R1 on 3b, R2 on 1b. B3 hits a grounder to F3, who throws home to F1. The throw hits B3 in the shoulder as she is running inside the diamond towards first base. She has run straight from the right hand batters box and is running in a straight line towards first base when she is hit by the throw. I know what the MLB ruling was on the play, but what would the ruling be in softball (all rule codes welcome).

Nothing. The runner's lane only applies on throws from the area around home plate towards 1st base. If the batter does nothing to interfere, then it's a legal play.

Where does it say that? :confused:;)

It does not explicitly say that, but this article from Referee explains how runner's lane rules work. It says that the throw must come from the area of home plate.

Unless softball is different, runner's lane rules only apply on throws to first base. This was a throw to home plate.

Neat. Author's opinion. FTFA...

Another requirement that triggers the rule is the “origin” of the throw. Although that is not specifically addressed in the rules, it is understood the throw must be made from “the area of the plate.” The originating area is not a precise one and it allows umpires to make a distinction between throws that are roughly parallel to the first-base line and those made from the infield dirt or the pitcher’s mound. The restriction applies both to batted balls and uncaught third strikes. It does not apply on throws in the opposite direction. [...]

my emphasis.

I won't bother to look up the small ball rules. Softball states runner's-lane interference is when the batter-runner, in the last 30 feet, runs outside the running lane AND interferes with a fielder taking the throw at first base. Says nothing about where the throw originates.

OP's case is not interference unless batter-runner does something to intentionally interfere with the throw.

And being hit with the throw is not interfering with the fielder (in spite of the visuals in some videos), nor is the catcher not throwing because the BR is there.