As far as behavior rules all 4-legged creatures in my house are subject to the same regulations.
Because of the size difference between my Dobe and my Yorkies, for their safety, I do not allow them to run together. Play is fine but my Dobe knows that he is not allowed to run around with them so he will lay down and play that way.
When we go to the park, the Dobe gets to run off leash first with the Yorkies in my arms and then after he is on leash the little ones get their turn.
With a bigger dog all it takes is one mis-step to cause a potentially life-threatening injury to the little guys. Keeping this rule keeps everyone safe.
I know its a bit different from what the OP set out to find but just thought I'd share it with all of you that have major size differences between pets. Hope this helps!