Can the biological Father claim that child

salam!

My question is that in 2001, my aunt who was in ICU for her cancer treatment gave birth to a girl n died in hospital some 8 days later, that child was brought by my father to our home after permission from uncle (Chacha)…
Now the child is 20 years old, studying at Uni in Islamabad.
Her father’s name on B-form is my father.
Her CNIC also mentions the name of my father as her father.

Now the issue is, due to some circumstances, the uncle(chacha) says, that he will take her from us as he is the biological father of the child. My question is, Can he under any law? Will it depend entirely on the child’s willingness to go with his biological father or not? what is the procedure in such cases?

Regards
Muhammad