Thanks, everyone, for your replies. After she got the marrow out of the middle, Maggie would most definitely bite down on the bone and my concern is that she might crack or break her teeth. I think I'll wait until she's a bit older and her teeth are stronger before introducing her to soup or knuckle bones. I learned from Carmen Duggan (Maggie's breeder) that bones do not splinter unless they're cooked, but I don't want her teeth to splinter either.
I have always given my dogs people food (as in save them some of what I'm eating, like toast, beef, chicken, fish, veggies, potatoes), but I'd like to wait until Maggie is a bit older. She loves her kibble and I use dog biscuits for training and as treats.