Wow...I might be wrong on this one but I don't remember it being this complicated. I will only refer to a three-handed game after one player is eliminated.
Alice Button...Bob SB...Carol BB...If either Alice or Bob gets eliminated the Button goes to Carol. If Carol gets eliminated the Button will advance to Bob. It does give Bob the SB twice but Alice would have been the BB on the next hand if Carol were not eliminated. I could be wrong but I think it's that simple.