2 Year old Shih Tzu girl Adopting to New Home/Family.?

We adopted 2 year old shih tzu girl, which was alright with us when we saw her in family's house (they had other dog also), but when we got home with her, she started to be aggressive towards us,like wants to bite when stroking her and also lashing at my other dog (3 year old yorkie girl)when she goes to smell her, family gave us blanket which has "their" smell on it which she now laid down on, but how long does it take to get used to us? Our house's "smell" etc. Anyone with similar\ experience? As family is emigrating, I don't want to take her back as I fell in love with her, but her behaviour is making me sad.Thank you.