This is the most painful thread I've ever followed here at BYC. I had nightmares last night about your situation.
You will be in my thoughts for a long time. I surely agree about trying to treat them, but I would add that if one of YOUR original birds dies of this thing that you have a necropsy done. Some states have that service for not a lot of money, and it might save you from a lot of later worry. It is better to know than not. If they are ill from an unrelated source (not likely, but possible), you need to know what the infection is.
Please let us know what happens long term -- in 2 or 3 weeks at least.
My condolences for your losses.
Sharol