You probably have already eaten it by now, but the general answer is probably:
(1) Yes, you can generally add fresh bones or other things to a pre-existing stock/broth and cook it some more. This is traditionally called a "double stock," and is sometimes deliberately used by chefs to get a more concentrated flavor.
(2) "Would it be okay?" Mostly, yes. It shouldn't ruin anything. However, there are some flavors that will begin to break down with prolonged cooking. So if your broth included some more subtle vegetable or herbal notes, for example, they might be lessened if you continued to cook it for a long time. If I planned to do this, I would taste the stock again about an hour or so before I planned for it to be done and add back additional fresh flavor components if necessary to rebalance it.