[Opinions] Re: Katherine/Catherine
If the reason you don't see your niece Catherine has to do with a falling out, then I'd be a little surprised if you would want to name your daughter the same name. If it's just for benign or geographical reasons, then I think it'd be just fine to "reuse" the name. If it was me, I'd just keep it to the middle name spot, personally.
I think Willow Catherine has the nicest ring, of the three options.
And, as you have probably guess, Cathering is my preferred spelling.