If you want your old gal to continue to have protected (alpha type) status you should protect it for her, from the pup and middle dog.
Sometimes the top dog does not seemingly do a lot to enforce his or her status, but it's happening and the other dogs just sense it.
I'm sure they do sense it, but that's more about me and how I treat her, as she
does nothing to enforce anything. She just goes with the flow. She doesn't care what the other dogs are playing with. She just checks them out and the look on her face is something like, "You two are idiots, look how smart I am, I'm in mom's lap or in my comfy bed."
But maybe she's giving off doggy vibes I don't feel/understand.
None of my dogs compete for toys, I may hear a whine from one when one is chewing an antler or something, but never growls. They are out together unsupervised with their toys/chews no problems.
If I were to add another dog to the pack, I'd step up NILIF for all and put away the toys/chews until the dogs settled the dynamics more.
I think when we, the dogs people are present, the resource guarding, jealousy of attention is heightened, so more problems arise when we are around.
It is always the middle dog, the Shiba, who "steals" the toy (usually in the middle of a game of indoor fetch with Bailey), and Bailey whines about it. I can't blame him in one way - we're in the middle of the game and the Shiba grabs the toy and runs off with it. I've backed off playing the game when the Shiba is in the room. I put her in another room for these play sessions. But I know that is not really dealing with the issue.
They've never fought, nor even had a "squabble," YET, because Bailey backs down to her. I know that day will come that he finally tests her seriously. That's why I need to learn more.
Pack order is usually established with dominance and submission displays more than fights. A lot of it gets worked out in playing; they get an idea of who is stronger, who has more will, who is dominant during play.
Rocky has been the dominant one, first with Cash and then later with Kopper. I don't think you can make one dog higher in the pack order than another. They know when the humans are propping up a dog that can't stand on its own. I think that no good can come of artificially elevating one dog over another that he/she is not naturally dominant over. However that does not mean the dominant dog gets to do whatever he/she wants to the more submissive dogs.
Rocky has always been a very fair pack leader. He mediates disputes between lower-ranking members, he enforces the rules, he doesn't pick on subordinates. If there ever comes a day that Kopper becomes dominant over him I can't force Kopper to be submissive, but ultimately I am the alpha and it's my job to protect the weaker from the stronger.
Very interesting. Lots to think about there. So far Bailey submits to the Shiba. My worry is the day he won't anymore.