Sometimes a FWB I've hooked up with multiple times before would ask "How do you feel about us?", "What are we?", "Are you seeing anyone else?"

How would you respond to these (any guides you can refer me to)? I'm looking for a more graceful way to navigate these interactions to either (1) Keep her as FWB or (2) Promote her to Girlfriend status at the expense of the other girls I have on my roster. I'm also having difficulty in knowing how much to reveal (i.e. should I be upfront and tell her that Yes, there are other girls I'm seeing).

This is obvious a critical/serious discussion and I want to be graceful in dealing with it.