Please Help

Hi, this is nothing related to the Human Body, but I really need help. So last night, I(in a way) adopted my brother's babysitter's neighbor's dog. Let's call the neighbor Farah. So Farah seemed to have a really good relationship with Bella(the dogs name) and once I took her into the car, she started whining and sniffing around for Farah(sad, I know 😩😩). The thing is, I have no idea how long Farah has been having Bella, but now she won't stop whining and waiting at my bedroom door. Bella has kept me up the entire night and it's currently 04:36. Farah has given me advice on how to make Bella "feel at home"  and one of them was to leave my door open so she's free to run around, but I don't think my Stepdad is ready to see Bella freely roaming around, given the circumstance that Bella was just brought home without asking for consent. Anyways, back to the whining, I noticed that Bella would stop whining whenever my Mom is in her presence. Bella would just be calm or content because of this, I kept calling my mom over to my room just to help, but whenever she left, Bella would go back to whining...Is there anything I can do to stop the whining without having my Mom constantly come into my room?