Please, some advice would be appreciated.
My heart is breaking!!!!
Oh, sad. @mskupcake
We had something similar here. Romy and Michele were rescues - adopted into our flock together. BFFs all the way. They integrated quickly and well into the flock with the Runners. They always were a bit on the outer edge of the flock, but everyone seemed to get along fine. Shelly died of egg yolk peritonitis, suddenly one morning. Three days later, Romy was showing similar symptoms and I took her to the vet but nothing was found. I felt that she was grieving herself to death.
We got her through that crisis, but then the Runners started ostracizing her. Nothing brutal, but chasing and excluding. I felt so bad for her. It took a while, but we adopted three more Buffs. And though it took longer to integrate them into the flock, Romy by then actually seemed to prefer the company of the Runners, and the Runners, in fact, got really put out with Bean the new Buff drake for making time with Romy. They would literally argue over her!
These days, the three Buffs have their own pen, and Romy is an honorary Runner. Ducks are weird.