Bill covered what might happen, and yes, frogs should be similar size, otherwise smaller one might become food or just being bullied badly.
what i wanted to say is quarantine should be for at least 60 days, if it is CB frog, way longer - 6 month for WC before you introduce them to each other. during that time fecal exam should be done, for WC - a few fecal exams. and actually i would very very strongly advise to get a cb, wc whites might be headache from vet. perspective.