http://www.strachan.dk is always a great place to start researching; Christian C. Strachan has done a lot of hard work collating the stemmata from the plethora of prosopographical studies.
Women have their uses for historians. They offer relief from warfare, legislation, and the history of ideas; and they enrich the central theme of social history, if and when enough evidence is available. Ladies of rank under the first imperial dynasty are a seductive topic.
Ronald Syme, The Augustan Aristocracy (1986)
To continue from the thread on interests on the Rubellii: http://www.strachan.dk/family/rubellius.htm presents a stemma - with a small mistake, it should be "or dt of R109" for Rubellia Bassa. Hence it is far from clear that Bassa truly was a member of the first dynasty.