Relative pronoun in “Ce n'est pas ____ elle veut parler”

Question

"This is not who she wants to talk to"

Ce n'est pas ____ elle veut parler.

In a related question, it was pointed out that we can say

J'ai oublié à qui elle veut parler.

In the case with the verb être, however, I don't think this would work. Do we have to use ce à qui?

Answer 1

I see two ways. Indeed, one uses celui/celle à qui, like you mention :

Ce n'est pas - la personne à qui - elle veut parler.
This is not - the person to whom - she wants to talk to.

and :

Ce n'est pas - à lui/elle - qu'elle - veut parler.
It is not - to this person - that she - wants to talk to.

Both mean approximately the same, with slight nuances.

Answer 2

In this case I would say the following even though it is not a very nice way to say it.

Ce n'est pas à elle qu' elle veut parler.

Which litterally means

It is not to her she wants to talk to.