What should happen when a jack delivered by player "A" goes into the ditch?

When a jack delivered by player "A" goes into the ditch, the rule that applies is that the jack is deemed dead, and player "B" has the right to deliver the jack again. This is consistent with the laws of lawn bowls that state if the jack is delivered into the ditch and there is no touching the jack prior to it entering the ditch, the end will not count, and player "B" can initiate a new end by delivering the jack themselves.

This process ensures that the game continues fairly after an invalid delivery of the jack. Therefore, it is appropriate for player "B" to take their turn in delivering the jack without any input from player "A," as the initial delivery has not resulted in a valid position.