Jealous Dog with New Puppy - Help?

I have four dogs. Mackie 9yr Shep mix, Bella 4yr cockapoo, Karma 3yr Boxer and Flash a 9 week old Border Collie.

Mackie and Bella I have had since they were puppies. I adopted Bella because she was very sick and nursed her around the clock for the first 3 months. I was raised around big dogs - so she was my first “little” dog. Subsequently she has been babied and even though I know better - the household dynamic worked and everyone was happy.

Earlier this year my partner moved in with a 3yr old Boxer who, I integrated into my pack and I am still working with her. She has a high level of anxiety and is calming down gradually. She has really made terrific headway.

I just brought home a Border Collie pup and he is fantastic. He is an absolute sponge, his confidence level is building - he is problem solving and is learning basic commands just from watching the other pups.

Everyone is getting along and getting to know each other at a pace I am very happy with except my 4 yr old cockapoo.

She is jealous and possesive. She peed on my bed (where she usually sleeps - not any more - since that incident). She is aggressive towards the pup and you can feel her body language to be tense and hostile.

My response to the peeing and the aggression is - I have started to check her more and have cut off her privelleges to the upstairs of my home. She is now crated at night and is now being fed last. I am trying to send the message that this is my home and it is my rules. If she continues her behavior she will remain demoted in my packs rank - below even the new puppy.

Pre-puppy, I fed my Sheperd first, her second and the Boxer third. I am now feeding my sheperd, then boxer, then puppy, then her.

Surprisingly to me - the Boxer has really calmed down with this change and her anxiety level has dropped noteably. Which is awesome!

So - now I’m at a cross roads. I’m not sure if my approach is correct or how I should go forward from here.

I’m looking for help and advice.

I love to train and all the dogs love to work for me. I have done agility and obedience with my two and am working on obedience with the Boxer.

I really want to spend time bonding with the new pup and put my energy into training him but I don’t want to antagonize the current situation.

(everyone I know usually calls me for dog behavior advice - but now I’m the stuck one!! Please help!)