which doesn't change the facts.
He has no rights to claim Frisha for his own, nor does he have the power, he could make Emilys live hell by opressing her, but he couldn't actually steal Frisha from her mother.
Couldn't he now? He's not above tricking others, experimenting on them and abusing his power as mayor (and later, as baron).
When Emily first had Frisha, Giron dumped her so she had no intention of revealing Frisha to him. Had she done that, due to her precarious situation at the time, nobody would've bat an eye had he locked her away. They wouldn't even have noticed somebody had gone missing. Or he could've smeared her name, like what happened to Sabrina. At that time, he could've stolen her away from Emily, no problem.
Then we reach the time when Frisha and Dave are grown up and they start pseudo-dating. Marcus is still alive and still protecting her. However, money is growing thin for the both of them. If she were to reveal Frisha's ancestry, Giron would've shown them both no mercy anymore when it comes to taxes. He could've also made both of their lives a living hell... or threatened her to do so if she doesn't accept to giving Frisha to him. For instance, Marcus could've been sent to the frontline. And if he gets killed there or has an "unfortunate accident" along the way, that would've been the end of that. As for Frisha, with the way she was back then, she might have said "it's ok mom, I'll be supporting you that way AND living my dream, so it's all good".
Plenty of scenarios to imagine, so long story short, nothing good could've come from confronting Giron. She has no power, she can't pay her taxes without Marcus, both Marcus and her lack money, and Frisha was looking for a way to get a more lavish lifestyle to escape that poverty. Forgot what I wrote exactly (lost it due to the automated site backup), but there's a reason why Emily wasn't exactly a happy person at the start of the game.