I've had that on an Isthmian League game. Referee injured, no 4th official, and the away club refusing to accept the qualified L5 referee who coached the home club's youth team. League rules, and I suspect the early FA Cup round rules are the same, say that where there is no agreement the remaining two officials will finish the match. Once the away club realised it would be their defensive line that had no AR they had a change of mind and agreed to to the home club official running the line.I recall there was an FA cup 3rd round tie a few years ago, where the Referee and 4O both went down. One of the AR had to take over in the middle but the teams could not agree on a replacement AR (as the one who volunteered was on the non-football staff of the home club). They had to finish the match with just 2 officials.


