it could have been formed from the matter in the Mutara nebula (unlikely since it was scattered by the explosion) or it could be the transformed Regula.
In that case, why does anyone
ask any of these questions if, by your strict definition of the rules, they cannot be answered.
Your comment about Uhura doesn't make any sense, btw.
Did we witness her birth on screen, or did dialogue reference it? How do we know it happened?