Posted:
In the fisherman story Parvati does not leave her body...She just dissapears from kailash and take the form of a baby in forest...She is adopted by the fisherman and grows up to be the same parvati...she wont be born from a womb
In Sati's case Adi Shakti destroys her Sati body so change of actress was required.
In this case its just one of her Leela...there are several stories of Shiv and Parvati taking differnt form...I dont think they'll replace the actors for every story.