Forgotten child

Hanji decided to test her new experiment on Levi and Eren. Both males intensely wanted a child but dew to the fact it was physically impossible for them to have one hanji used her experiment to help. She made a machine that took the DNA of both parents and formed a child. The child grew and developed like normal. She was extremely loved by her fathers, Hanji and others from the survey corps. However commander Erwin soon noticed the survey corps was no place for a child.
Neither Eren or Levi could leave the survey corps and so the child was sent to the undergrounds where it trained itself to survive.
10 years later a young girl is captured by Erwin in the underground. What is she hiding? Will she be recognised? Who is she?

Ok so this is the main idea. This is my first ever fanfic so don't expect much from it. It'll probably contain swearing but if anything else is planed for a chapter I will put out warnings.

I do not own any of the SNK characters I do not own SNK either. I also don't own that picture i found it online. I only own this storyline. Enjoy