I would take them to a vet and have the vet treat them. Birds should only be treated for mites if they definitely have them- it's not a preventative thing like flea treatment for dogs. Although they sell over the counter sprays, etc I wouldn't use them. A woman on another forum that I knew used an over counter mite spray on some birds she was carrying for and they died. So if your friend suspects mites, I think she needs to see a vet.