bird sitting

[Virgogoddess]

So my friend calls and tells me her ex-husband is losing his place and has no where to keep his birds and can I help out and "foster" them for awhile. He has two cockatiels. His bird is named Ozzy and 10 years old. Her bird is Paco and is 4. Paco came to live with him this year when my friend was diagnosed with COPD and couldn't keep her anymore. I have a cockatiel and a Meyer. They are both 6 months old. Paco is available for adoption but Mark definitely wants his bird back. Ok so, in come the birds in their cage and I notice after one day that the female lutino, Paco sleeps a lot. She's fluffed up. I know, take her to the vet, right? The other one is fine. I wonder if I should give her a little bit of time to settle in, I know she has to be totally stressed out, right? I was going to probably end up keeping her and see if she would like my cockatiel. Now I'm freaked out and I think my friend should pay for the vet visit. Any suggestions?