Obedience classes do not address aggression issues. Otis would need to see a behaviorist who specializes in aggression to get qualified help.

If it were me, I would try that before just giving him up for adoption. Dachshunds are pretty bad nippers/biters but sometimes the problem can be addressed. I would be baby gating my house to keep the dog seperate from the babies. But I would still be sure to spend a lot of quality time with the dog (when babies are napping, etc).