Far as dog aggression goes Im relieved to say we' haves no problems at all. This is a huge plus as dog aggression can be quite problematic to have to always have to manage.
I suggest close inspection at any breeding facility as dog aggression is very easy to pick up. Look for the tell tale signs of scars, get the parents out one by one and watch them run through he kennels, notice the responses of the other dogs and it etc. Also go at feeding time, watch the puppies being fed, if they are happy its a good sign, if they are at each others throats look at another litter. I've seen and indeed unfortunately had litters that behave like Tasmanian devils at a carcass over their dinner, even the bitches teats, avoid! You want nice happy puppy feeding sounds and contented grunts.
Ours are fine with each other, one male and three unrelated females. We also have house dogs, a couple of quite extreme JRTs, no problems, they will voice a deep grumble to protect their chews and bones etc but otherwise are even playful with the JRTs. The JRTs know BTW exactly how to appropriate their chews and bones using stealth. They will wait for some distracting commotion or other, like a passing hiker then when I come out to see what's up they make a dash dragging the quarry straight into the front door before the big guys return. We do take all sensible precautions around feeding times, though.
Strange or wild dogs on the other hand are absolutely not tolerated at all. Seen as predators by both sexes.
Sometimes a pack of wild dogs will run through here at night chasing small deer, this elicits the most serious of responses from the dogs who will bark for hours and hours until they can no longer hear or smell the pack. This can drive us insane if the wild dogs manage to take something down not far from our perimeter fencing. Between the wild dogs and ours the noise is just tremendous and goes on and on and on. Luckily this is also not very often, though once the deer managed to leap the fence straight into the garden and we were up all night trying to get it out to get rid of the wild dogs and the commotion it was causing with ours. It kept running into the fence and everyone was going nuts so we just gave up. Didn't sleep a wink but by next next morning it was gone. Quite often deer of all kinds leap over the fence, early dawn and dusk and graze on the lawns keeping them nicely trim, these are ignored. Primates are not tolerated however at all! either. In fact anything causing a commotion in a tree is suspect this includes squirrels during the day and bush babies at night who are unfortunately noise wise seen as tiny primates, they're half right at least.
These dogs are not for those who can't turn over in their bed and fall asleep again to the melodic sound of mad dog. You learn to recognise pitch and so know when it's appropriate to get up or not.
Im not sure if this is pure coincidence this lack of dog aggression or it's the lines or even this particular male and these females as individuals or even our influence or circumstances, but as I say it has been a huge relief. We didn't choose our present dogs as such so just got lucky perhaps.