Is this a real thing that could happen? We’ll have to see what our data provider gives us. I have no idea.
My guess would be:
Anyone who switched teams since April 11 and plays in today’s Marlins-Mets game will be treated like a player who played in a doubleheader - they’ll have two games counted towards games played caps and will get stats from both whatever game they played in back on April 11 and whatever they do in the resumed game. You will have to have played that player in your lineup back in April to get their stats today.