I found out today through official channels that the drummer at the Fiesta Bowl was Anthony Citrinite. And I looked around at Kimberley Dahme's website and by the looks of it, she was only in for the Fiesta Bowl performance (in other words, a one time gig). Since she has at least one other gig booked elsewhere this month (according to her website).
That would mean that Antonio Cosmo is probably the permanent bass player in the band, but just filled in on guitar for the New Year's gig (this is just my speculation and not official info). Of course, that would probably mean that the tentative lineup of the band is (and this is just my speculation):
Tom Scholz Brad Delp (vocals/guitar) Fran Cosmo (vocals/guitar) Anthony Cosmo (bass) Gary Pihl (guitar) Anthony Citrinite (drums)