Maybe I'm too late? How about Chinchillahs??
My thoughts: I'd nix the 'tiels and the ferret idea. Both require tons of attension. Ferrets are no different then ownin a puppy and they keep that engery into adulthood. Tiels or any bird really requires time, effort, lots of maintence and good base knowlege just like herps. You cannot go out an buy a bird with no workin knowlege. The animal wouldnt be very healthy. And the bigger facter. ALL birds have a tremendous lifespan and some can easily outlive a single person. Your typical finches will live a good 10-14 yrs believe it or not if cared for properaly. I dont believe the Father would want an animal older than him! LOL!! Since he sounds a bit picky with pet options.
Maybe also suggest havin the daughter and the FAther just talkin and writing down names of the animals they both agree on and single out ones they would want to care for on the list and purchase a book on the animal to read first.