>>49617342>prequelNTA, but the more I think about it, the less sense it makes. Ib has to be the protagonist or the game's title just wouldn't add up. You could toy with the idea that she went into the painting sometime in the past and simply lost her memories. But then, Mary would surely remember her, so that can't be it.
We know Guertena was obsessed with the girl in red, who was aparently based on someone he loved in life, so maybe making that someone Ib's mom could be more significant. The problem is, Mary would recognize her in the "Together Forever" ending, which also ruins the idea.