The premise of my book relies upon the use of multiple races in my book-world. I haven't read much contemporary fantasy, so please let me know if any of this is not acceptable...

I have a race of nymphs. The females manifest as tree nymphs (draiads) and the males are water nymphs (nyads). The idea of separating the genders comes from the traditional idea of female fairies and male brownies (which I also have in my world).

These four (draiads, nyads, fairies, and brownies) are all "persons" in that they have souls.

Here's where things get a bit complicated.

When the nymphs reproduce, fairies/brownies are born. These then help to propagate the growth of new trees and streams (AKA draiads and nyads). So it's almost like every other generation is nymph kind and every other is fairy kind.

Does this make any sense?

I think it makes sense. And it's quite creative in my opinion, too.

It makes sense, I think, and I agree with Milly that it's very creative.

Are you deliberately using nonstandard spellings? "Dryad" and "naiad" are more usual than "draiad" and "nyad".

Oops! No I did not mean to misspell those. Thank you for pointing it out!