There's a story entitled "Ranma's Rebellion", matching the description you provide, of which two chapters were posted to the FFML in June of '01; it's by Donovan A. WIllett. I don't know where it could be found online (although I have the aforementioned two chapters), but the author's name may help you search. If you find more than those two chapters, please let me know; I was looking forward to more of this, back in the day, but nothing ever turned up.
I have a story - claiming to have been posted to the FFML Refugee List in July of '01 - called "Cherry Blossom", by Allyn Yonge (AKA Desaix); I haven't read it in detail, but the setting seems to roughly match what you describe, although Ryoga's name does not appear. Again, no certain idea of where to find it online; the story does include a URL for the author's fanfics, but it's Geocities and dead. Desaix does have a fanfiction.net page under that name (his current main project being a Naruto fic called Training for the Job), but I don't offhand remember seeing this fic on that page.
I have a story - claiming to have been posted to the FFML Refugee List in July of '01 - called "Cherry Blossom", by Allyn Yonge (AKA Desaix); I haven't read it in detail, but the setting seems to roughly match what you describe, although Ryoga's name does not appear. Again, no certain idea of where to find it online; the story does include a URL for the author's fanfics, but it's Geocities and dead. Desaix does have a fanfiction.net page under that name (his current main project being a Naruto fic called Training for the Job), but I don't offhand remember seeing this fic on that page.