This is a hard one for me to answer. Two weeks ago my Maui was not doing well at all. He was floating on his side, belly bloated, gills barely moving, and every hour or so he flopped around hard. I was making plans to euthanize. I thought several times that he had passed. After doing research and talking it over with family, since he is my baby, I decided to wait a day. He had already been like that for a day when I made that decision. So after two days of him looking dead, I woke up to him swimming around happily, back to his normal self.
I have no clue what happened. I am glad I didn't euthanize and I am hopeful he will live a few more happy years. I've even moved since then and he made the 14 hour drive just fine. He is doing great now. That being said, I know how hard it is to watch them struggle and how painful a decision this can be. I don't know your fish and her background like you do. I read this article: http://nippyfish.net/2007/02/12/euth...aquarium-fish/
And it helped. Maui was not able to right himself when he was like that, but he still showed signs that he was fighting. He even ate food pellets that I dropped near him. So, I can't tell you what is right, but maybe this information helps some. I feel for you and Maralynn. I wish you the best and just know that you are being the greatest fish parent she could have asked for.