Or did they add her after they changed the entire script after Chadwick Boseman death since Marvel Studio didn't want to recast the T'Challa Character and made Shuri the main character?
They probably added her into the movie. But from what I remember, it was gonna be a father and son movie with T'Challa's son we saw at the post credit scene of Black Panther 2, and it was gonna be a little emotional movie, because he never got the chance to be the father, because he was dusted for 5 years. But Namor was still gonna be the villain of the movie.
