Just some odd idea I had. A talented girl from the Joketsuzoku village is the victim of a cruel joke and ends up running away, where she ends up falling into a spring at Jusenkyo. It doesn't necessarily have to replace the regular drowned girl spring. It doesn't have to be a girl from the Joketsuzoku village either, but it may add another dimension to the curse if the girl-away portion needs something extra.
The girl-away girl spring is a combination of the girl and the that girl-away stuff, so the one cursed isn't affected by the girl-away since they are the source despite being a girl. Ranma doesn't have to be the one that falls into this spring, but he's the most likely to be used.
I've thought of both silly and serious scenarios for this, apart and together, so I thought it best not to outline any particular path to follow. I don't think it would be that hard to explore the what-ifs of how this might affect where things go, anyway (since I think there are a lot of options). In some ways it might help someone like Ranma avoid certain problems, while also creating different ones. Visiting the Joketsuzoku would almost certainly play out differently, especially if the curse also produces a Joketsuzoku (whether they're talented or not). The meeting with the Tendo sisters is likely to go differently, as well, and perhaps not for the better.
At some point the effect of the girl-away could be suppressed or cured, or Ranma could end up (accidentally?) changing the effect to affect males instead of females, either as a girl or somehow reversing it entirely so it's in effect while he's a guy.