|Message:||Does he have some way of handling her without getting bitten? Will she step to a perch, perhaps? Working with a bird that's determined to bite the shit out of you is tough even if you truly love parrots. I can't imagine a non-bird person staying calm and patient with a little biting monster. Can you trust your F.I.L. to handle the biting or screaming in a calm and rational manner when you are not around? If you are not sure, consider boarding Sammy, or having someone with more bird experience take care of her. It's always good to have friends with whom you can trade bird-sitting visits. That's what I do...
You probably need to evaluate potential prob's and teach your F.I.L. to avoid them. Most often, I get bit when I'm trying to open the cage and when I'm changing water dishes, so the safest thing to do is to distract, quickly open the cage, and move the bird onto a playpen or cage in another room while cleaning and feeding. Pick up the bird on a rope or dowel perch if she's determined to bite hands, don't reach into her cage. Don't let her out unsupervised, and always make sure of where she is at any moment, when she's out.
She'll probably be in the cage, most of the time. That's fine, if she's got enough interesting things to do, and cleaned, and fed and watered. She will not be traumatised by 5 days of this. At first she'll be mad, then sorta unhappy, and then so desperately glad to have you back at all that she'll stay glued to your shoulder for the first day or two. That's how my guys are. If I'm gone for a day or two they give me the cold shoulder treatment, but if I'm gone for a week, they grab onto me and don't want to leave.
My cockatoo is most bonded with my mom, and when she is gone, he does not want to come out of the cage at first. I just make sure he has plenty of toys, clean and feed him, and spend time around but not directly interfacing with him. Letting him make the first move. In 2-3 days he starts coming out and rather obviously sucking up to me, I guess any attention is better than none. Maybe Sammy will get to trust your F.I.L. more if he's the only one she can interact with?
My conures are in a flock so they just scream alarm calls until the intruder changes food & water, and goes away. They are more friendly with each other than any strangers. They don't care who it is, if I'm not there.