I"ve owned them in the past and have another now. Funny thing is that when my daughter was 2 ( the first time we had some) she loved them and there was one female that she handled contantly. But this time around at age 9 she is afraid to handle the new one because she doesn't want to get picked. So, I wouldn't really recommend them for this little girl. Her father probably wouldn't like it if it turned out to be a popper or shy hedgie which many are. They are wonderful, awesome pets but seriously her father doesn't sound like the kind of owner for these guys. I would take a rat over a hamster any day, those buggers bite all the time! Rats are much more docile and smart. lol
But I would say go with TexasAggie and get a guinea pig. My daughter also had one of those. They can be quite vocal though so if that would bother the father that too would be a problem. Ours learnt the sound of the refridgorator and would squeel with delight every time it opened because she thought carrots or greens where coming her way. lol. We called it the fridge alarm.
He could also go with a female bunny. Males spray so I'd stay away from them, but a female dwarf rabbit would make a great pet, they can be housed in a large guinea pig cage and are pretty easy to care for. Another great pet would be a cockatiel. My daughter loves our bird. If you get a hand raised tiel at a young age they can be very pleasing as a pet. They love attention and will sit on your shoulder and eat from your hands and give you kisses.
Great pets. We have two tiels.
Hope she gets her pet and the father doesn't change his mind afterwards.