Re-watched Amba's scene.. looks like her problem is with the Chavan baggage Sai will bring with her. She don't want Chavans coming and going in her house and disrespecting everyone there. Which is a fair decision. But since Savi will be staying with them, Chavans will keep coming there and disrupting their peace. Can't blame her. No sane person wants daily tamasha in their house except Chavans.
I don't understand why people think she mentioned Savi as manhoosiyat. I didn't feel she was even thinking about Savi. She was clearly speaking of Sai's past and present connection with Chavans as manhoosiyat (which is true in a way. Chavans are bad for Sai, Satya, the kids and Adhikaris). I don't think Amba is wrong here. She is not against Sai or her kids, but rather against irritating, abusive, toxic Chavans.