Playing the wrong ball: consequences of not applying the rules correctly

The following situation:

When playing the fourth hole, two players swap their balls on the second shot.

When marking their balls on the green, the players concerned realised that they had broken the rules. Neither of them knew what to do in this situation and so they decided to finish the hole with the wrong ball. After completing the round and handing in their scorecards, both players contacted the competition organisers.

My question was whether they knew whether they had realised this mistake after the hole in or before. Both players gave me the information that they had realised on the green as they marked their balls that they had each played the other's ball and they suspected after the second shot that they had swapped their balls. My question was also why they finished the hole with the wrong balls, didn't contact the referee and went to the next tee: Their answer was they didn't know they were supposed to make this right.

My help in that regard was that I knew there was an interpretation but in this case it was no longer applicable

Rule 6.3a Interpretations:
6.3a/1 - What to do if balls are swapped in an unknown position
If two players realise after holing out that they have finished a hole with the other player's ball, but cannot determine whether the balls were swapped when playing the hole, this is not penalised.

Example: After playing a hole, it is realised that player A has holed out with player B's ball and that player B has holed out with player A's ball. Both players are sure that they have holed the ball they played from the tee.

In this case, and because a player may start any hole with any permitted ball (Rule 6.3a), it should be decided that the balls were swapped before the start of play on that hole unless there is evidence to the contrary.

There is only one ruling on this Rule 6.3c

6.3c Wrong ball
(1) Hitting after a wrong ball. A player may not hit after a wrong ball.
Exception - ball moving in water: It is not penalised if the player hits after a wrong ball that is moving in water in a penalty area or in temporary water:
-The stroke does not count and
-the player must correct the error in accordance with the rules by playing the correct ball from the original location or by claiming relief in accordance with the rules.
Penalty for playing an incorrect ball in violation of Rule 6.3c(1): Basic penalty.

In hole play
-If the player and opponent each play the other's ball when playing a hole, the player who played the wrong ball first incurs the basic penalty (loss of hole).
-If it is not known which wrong ball was played first, this is not penalised and the hole must be completed with the swapped balls.

In the counting game
the player must rectify the error in accordance with the rules by continuing play with the original ball, playing it as it lies or claiming relief in accordance with the rules:
-The stroke after the incorrect ball and all further strokes before correcting the error (strokes played including penalty strokes incurred only when playing that ball) do not count.
-If the player does not correct the error before hitting to start the next hole or, on the last hole of the round, before submitting his scorecard, he is disqualified.

As hard as it was for the youngsters there was only the decision of disqualification, yes ignorance of the rules is no defence against punishment.

In the meantime, if you would like to know more about the rules of golf, please contact me directly at hans.kienesberger@golf.at.