Courtesy runner in top of the 1st

[CecilOne]

Originally Posted by MGKBLUE

The other side is the interpretation we have.

The wording listed on the line-up means the line-up presented and accepted by the umpire during the pre-game meeting.

In this case we do not allow any such change in the pitcher or catcher originally listed until after they have faced the first batter in the bottom of the first inning. Therefore in the OP, the DP remains the DP for the top of the first inning.

I have not seen any interp that says "listed on the line-up means the line-up presented and accepted by the umpire".
I have not seen any interp that says the DP may not replace the FLEX in the top of the first. The "listed pitcher" rule is about CR and applies to whoever would be eligible for a CR in the top of the first. In the OP, that is the player listed as DP and pitcher.