I've never had a problem with bringing in new aspects of a character's history that was previously unknown. There are people you (the collective "you") have known all your lives who have relatives they haven't told you about. And why should they? If it comes up, it comes up.
This just happened to come up in a way that fans don't like. Well, too late. You weren't on the team supervising the script, and you can't go back in time* to change it.
*Let me know if you can go back in time. There are a couple of things I'd like to sneak past the TPD cops.