Nice. The twists and turns that are in here seem to flow gently and believably from one point to the next.
The only issue I have is the fact that Ragnok slipped the name of the Harry's guardian. I honestly think that will come back and bite Ryoga in the butt.
The ability to shift the Curse is a nice wild card, but curiosity asks what the result of an over-powered dispel would be. Would the original curse slam back or would the magic of the pools be happy with the chaos that occurs?
One thing that sounds funny, but still logical in a Ranma sense is the introduction of Ranma into Harry's life. The skills and experience of the youngest Saotome should be a goldmine for someone with the chaos rich future like Harry. That plus the fact that Kasumi would be a majorly helpful figure in any parenting issues that arise from rising Harry.
A strange thought just floated in: Is it possible to get a Wand / Iron Umbrella hybrid?
Think of all the options that would open up for Harry if he is trained in the use of the IU and it has a wand inside of it for magic casting.
Or how about a Wand / Bonborri (round hammer things Shampoo uses) combo?
That would be a way around the potential Magic/Iron rivalry.
Maybe Colgnone would give Harry lessons on how to use a cane similar to hers. That weapon would not be seen as majorly odd with the Wizardry world (Staff/Cane nearly interchangeable in British tradition).
The thought of a Kendo Sword / Wand combo doesn't mesh. Kuno goes thru those rather rapidly.
The only other Ranma Weapons that make sense to combine with a wand would be either Kodachi's Ribbon (Wand in the Grip of the Ribbon) or Akane's Mallet. I don't think the Ribbon would be all that useful and you are avoiding Akane so neither of them is getting my vote.
Then again, a Harry Potter (Hibiki) raised by Ryoga would doubtless be trained in many of the arts that Ryoga practices. The garment/weapon style would be a superweapon in Hogwart's, wouldn't it?
Anyway, I look forward to the next update.
JSX