K.M.
Ok, my son had two LARGE dogs in the house from birth, actually we got them as puppies knowing we were preggos and trained them for baby so he can/could do anything to those two. Then me moved in with Grandma who has Chewy a pomeranian/chiuaua (spelling) mix. Chewy was NOT having my son's play time since with his dog (only one now) he could be as rough as he wanted. Once we found a game they could play where son could be excited and maybe not as gentle they are BEST buddies and now they can cuddle and be gentle with eachother since they can also be rough. Chewy Catch! my son tosses Chewy's toy and then he runs after it and then the tug of war over the toy so he can toss it again, now a days they even almost wrestle eachother with the toy in my son's hand. So if you can find an activity they can do together that might get some of the aggressiveness that a young one has out but be rewarding for the animal you just might have a solution.
** until the common ground is found supervision is key.