I have two female Border Collies, now about 12 and 8. The older one is the mother of the younger, and the dominance issues we went through when the youngest wanted to assert herself... well, it took about a year for things to fall into place with the help of our vet and a trainer. (The younger dog is the dominant one.)
About 8 months ago, my son (same town) got a male BC pup as a rescue, and I volunteered to dog-sit as both my son and his wife work long hours. Of course he was the underdog, and it wasn't a problem (my girls weren't unduly aggressive.) After a few months, he was able to stay at home alone for longer periods of time, and we switched from the dog being here to my stopping in at my son's home to take him out and play mid-day on days when I was able.
The dog has now far outgrown both my females. He tries to be the dominant dog: he tries to eat their food, take their spot where they're resting, and sometimes much worse (he urinates on their beds and where they eat!) This causes all kinds of growling and snapping, and I correct his behavior, not allowing him to dominate.
The dog-owner in me knows there will be more peace ultimately if my girls just learn that he is now the dominant dog. Then there will be no more bickering; they'll know their place. :(
But my heart isn't in line with my head, and I'm not up for the months of disruption this will inevitably cause.
Should I just allow nature to take its course?
Edited to add: At my house, I treat my dogs as the dominant dogs. At my son's house, I do not push the issue at all, and there doesn't seem to be any fighting. I guess he feels a lot more secure on his own turf.