Pretty much my take on it - given that Kairi never did produce a true 'Nobody,' (though she was put into that category because of possibly other similarities by DiZ (or Nomura)) and Namine's ability to change Sora's memories makes sense because Kairi's Heart resided inside of Sora, and when he unlocked it blah blah blah -> Namine was produced, along with Roxas.
However, what really makes me wonder is how Kairi's Heart could have produced Namine from being released from Sora if she is a
'shadow of Kairi's Heart.' Kairi is a Princess of Heart, and essentially her Heart is pure Light, while Sora
does have Darkness inside of him. Assuming that
"with the greater Light, the bigger your Shadow becomes," it's feasible, but meh.
Also Grass I almost mistook you for goldpanner lulz