[Luckyday]

If she doesn't have any unique trait that is connected to her race and sex other then being "a human ally to the turtles that helps them in certain situations but slowly becomes part of their family".

You can do that with literally anybody over the course of the story.

Why not just create a new human character or re-use any of the humans characters that we have already at our disposal?

Like Keno from the TMNT II. It can be like a ET situation where he is like their kid brother or something.

If fans really want to keep her a straight white woman with red hair then do something with it.

Anything except what 2012 Nick has done.

But seriously just make a new character and just throw April in there if anybody start complaining.