2NT was (on request by South at his first turn to call) explained by West as natural.
When East passed with his second call South asked what was going on and was told that 2NT had been mis-explained, it shows a weak hand with (at least) 5-5 in minors. At this time I was called, and first offered North (as the last NOS player having called) to replace his pass with another call if he wanted to in light of the new explanation. He refused, so the auction continued as described with the clear understanding that South, who could not change his first call after the 2NT opening bid, would be eligible to a ruling after the end of the play if he would have called differently at that time given correct information and therefore felt damaged.
He called me again, and I had little problem adjusting the result effective for OS based on the accepted fact that South would have doubled 2NT and the result would most likely have ended up as 3♥N -2 with correct disclosure.
This was matchpoint scoring with 13 tables, The table result was (of course) a clear bottom -12 for NOS, 3♣W = would have given -1 for NOS and the adjusted result 3♥N -2 gave +6 to NOS.
My "problem" (if there is any) was if the re-opening double by South in this situation and/or the subsequent pass by North should be ruled SEWoG, resulting in a split score with OS receiving their -6, but NOS receiving -5 (the "normal" score reduced with 11 MP for SEWoG action)?
I shall appreciate comments.