Failed check or not, I do know that the Diplomacy/Wild Empathy rules do allow a re-roll if the circumstances change (In simplest terms, when something happens to increase your modifier)  So if Brandon ever gets a chance to aid another, the +2 to her mod should allow Callenda to re-roll even a failed check.<br/><br/>Not being able to use her charisma on animals kinda sucks for Theresa, of course.