10 week old German Shepherd puppy biting 13 year old GSD�s tail and privates?

If your old dog hasn't drawn blood than he knows the puppy is learning and is teaching him, not to worry, there isn't going to be a fight for supremacy, the old dog will always be boss but he won't have to prove it over and over, he'll just ignore the shenanagins. We're going through this righ now w/ a new adopted dog trying to be dominant over the dominant dog, Our dominant just growls that GROWL, we also have another older dog that likes to push the envelope, but he gets met w/ the same disdain. WE tell then to cut it out on occion, but it's them that really are working things out.