Going for help BBox
 

2 Outs
R1 on 3B, R2 of 2B
B6, Slap Hitter, at the plate.
Clearly clearly clearly has front foot out of the BBox when she slaps the ball through the hole. (BU sees it from C position)
PU does not see it
R1 Scores, R2 stays at second as F7 gets the ball to F5 quickly BR reaches
DC calls time PU grants time
DC asks PU to go to partner for help on batter contacting the ball outside the BBox.

Is this a situation where PU can go for help?
If BU tells PU what he saw and you were PU would you change the call to B6 out?

If I am the PU that is my call. I do not go for help because I need to see it. If I do not then it is not called. The only way I would go for help on that is if the catcher had tackled me or jumped in front of me. That is just not the BU's call.

Has the PU a white cane or a seeing eye dog .
The BU sees it from c position ?
Superman
The PU doesnt see it ?
Sarcasm yes as I find this hard to believe .
Methinks the BU is acting like a coach .
Hey its Friday night here in New Zealand , end of a hard long working week no softball for 8 weeks late autumn I NEED SOME RELEASE

So, let's see if I have this right. BU has two runners to watch leaving their bases, and is also watching the pitcher's feet to assure a legal pitch. BU is roughly 80' from the home plate area while responsible to watch 3 diverse locations away from home plate, then to shift attention to the plate at the last instant. Yet BU can see , even knows beyond a doubt that this front foot was touching the ground outside the batters box at the moment of contact. All this while PU, maybe 6' away, judges NOT to make this call.

IMO, BU needs to pay more attention to BU responsibilities, and leave the PU decisions and judgments to the PU. Have an opinion, fine. Would I (should PU) change call to a retroactive out? Not too likely.

First, an umpire can always go for help.

Second, if you are asked for help by your partner then tell them what you saw. No matter what a partner saw it's always the calling umpire's choice to change or stay with a call. No umpire can change the other umpire's call.

Third, the PU has to watch the batter and make those calls. I find it difficult for the BU to make that type of call but not impossible.

It is impossible to sell to both teams.

Who did BU tell that he saw this (in the actual OP)?

Coach? HORRIBLE.

Or were YOU the BU?

If my BU tells me at any point that he'd seen this (it would have to be after the game, as there's no chance of me visiting partner on this one during the game), I would admonish him for not tending to his own duties. No way does he see this unless he's ignoring something else that he's responsible for.

BU was hopping up and down on one foot spinning with both fists clenched
:D