Mets / Braves - Top 5th

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A question on mechanics with reference to this play:

Did the U3 (Dreckman) ask for help and therefore, there was a conference that ultimately led to a reversal of the call?

OR did the crew chief (I believe Davis) on his own call for a conference, and that ultimately led to the reversal (Dreckman changing his call)?

The report I read in the paper indicated that Davis called for a conference among the umpires first. If it did occur this way, is this an acceptable procedure for umpire crew (whether 2-man, 3-man, 4-man, or 6-man) to at least start a discussion?