Henny, what you described in the one you did the necropsy on was egg yolk peritonitis. It is treatable but it also means internal laying and an end to egg laying. That's what Gurtrude had, and since she is a pet first and foremost, treating her and saving $$ for surgery for a permanent fix is worth it. I'm pretty sure that isn't a route you're interested in taking unless it's a super special bird. Treatment is draining the fluid from the abdomen, antibiotics and pain medicine, and depo provera monthly. Gurtrude's depo is $16/month.
I'm sorry the same seems to be happening to miss may, but I know you'll make the appropriate choice for her.
Here the only bird vet is snobby and only treats larger parrots.

Trying to treat May is out of reach for me.
It is our reality.