Well, in answer to you question I will ask a few of my own....

1) How long are you (realistically) able to keep her in a closed off room without it being inconvienient to the rest of the family?

2) Where would she go if it REALLY did not work? (back-up plan)

In my personal opinion, almost all cats can get used to other cats, but how willing are you to disrupt you cat's lives in the meantime?