Don't get me started on Severe macaws and overbonding issues...
I LOVE macaws... but these are my least favorite bird to work with.
Severe macaws are THE WORST OFFENDERS when it comes to one person issues. Bottom line, this bird needs to be socialized with multiple people or, FORGETABOUTIT!
There is a disfavored person thread that I have posted. This one involves the favorite person taking the bird into a training perch and leaving the room. The disfavored person then comes in and does the step up and touching exercises. Then the favorite person comes back in and takes the bird back...
With an overbonded Severe? Watch your fingers, and have a towel at the ready! And what ever you do DO NOT BREAK EYE CONTACT!!! I have a scar (four stitches) on my thumb from one of these little guys slicing me open to the bone...
Once you get the bird to the point where 2 or 3 people can handle it, you start playing a game of pass the birdie, and the circle game. Both are training posts I've already detailed on this site.
Those are the hardest overbonded birds to work with. The best way to deal with this problem is to socialize them to the Nth degree to begin with and not allow them to overbond!
It's not that they are bad birds, it's that they are pair bond birds. And they are fiercely loyal to "the one." To the point of driving others off... (sometimes rather forcefully!)
That's the dynamic here.
http://parrotmusings.blogspot.com/2009/01/my-thoughts-on-severe-macaws.html
http://www.birdsnways.com/wisdom/ww45e.htm
http://www.drsfostersmith.com/pic/article.cfm?c=5059&articleid=2250
http://animal-world.com/encyclo/birds/macaws/severe.php
Every one of these articles says in some way, shape or form, that these birds tend to have "one person" issues. And my experience with them, with two noteworthy exceptions, has been the same as that expressed in the birdsnways article, and the blog. My perspective is somewhat different, as I was the one working with the "dumped" parrots. (Now you have a one person bird, without his one person anymore, who is angry at the world because he wants to be back with "his person" not with you clowns... "RE-SOCIALIZE THIS!")
With THIS MANY experienced people, seeing the same things I see... well, I'm not making this stuff up. And there was really only one species of mini-mac that got dumped, and they got dumped in short order.
Severe macaws are not necessarily bad birds. BUT they do require a higher than usual amount of socialization work, or they will bond with one person, and then it's a major pain (usually in the fingers) to rehab the bad behaviors. People don't do the work. Then no one else wants to get bit reversing the process, and the bird festers...
That tends to be the pattern.