Everyone gets along just fine in our house unless one has something remarkable and the other one wants it. This goes for the 13 year old Dane or Amber and has been that way for the past 16 years that I have had multiple dogs. When it comes to treats larger than small ones they can each sit and eat without the other taking it, I separate them until they are all finished. We had a knock down drag out over deer antlers not too long ago because I forgot all about some that were laying around. The Dane took Ambers antler and Amber decided she was going to get it back; Amber being short latched on to the Danes leg and it was on. We separated them, no one got hurt but we did make sure no more antlers were laying around. My moto is "divide and conquer." Each is fed in a separate location not in eyesight of each other and when no food is involved they are best buddies. Good Luck and I hope it all works out.
So glad housebreaking is getting better! Thats a big battle in it self!