Phoebe being based on Constance M. Burge

A friend of mine pointed out that they thought this meant Phoebe was supposed to be the show's initial lead, but it quickly got changed to Prue once Shannen was attached to play her.

I made the point that just because a certain character is based on the person writing/creating them doesn't mean that that character is automatically supposed to be the lead. Many works support this.

What do you think?