your parish probably calls it RCIA as a kind of shorthand for all sacramental preparation for adults. As I say, perhaps you class includes adult Catholics who need confirmation and/or 1st communion, adult baptized Christians seeking full communion with the Catholic Church, and unbaptized adults seeking baptism and full initiation in the Catholic Church.
Adult Catholics do not participate in the Rites of Christian Initiation, other than of course the sacrament of Confirmation itself. They are in a class with other adults for convenience–since for all intents and purposes, you all are studying the same things on the same timetable. But the loose use of the term RCIA does cause confusion. They definitely should NOT be dismissed after the Gospel with the unbaptized, because they are required to assist at Mass, the entire Mass. What you can do is be present for the others in the class when they do celebrate the various rites.