Apologies, this suggestion already exists
Suggested by FabianFnas in Thread 83035
Allow us to annotate every move as we play and store the annotations in the pgn. This would ideally be similar to the notebook but:
a. Larger, the size restriction on the notebook makes it hard to use.
b. Persistent by move. It would then be in the pgn and visible to that user when viewing the pgn (or emailing pgn to themselves) or reviewing the game on RHP.
c. Not visible to anyone other than the player who annotated/played the game. Clearly both players annotations would need to be stored separately.