I must admit, it took me a while to get my bearings with the prologue to our current read. Smith's Dictionary of Greek and Roman Mythology and Biography has a family tree of the Aemilii Lepidi. The Aemilius Lepidus who is the subject of the novel is shown as No. 17. The article on his father's career is No. 13 on pages 764-765.
For the ancient sources see the index for Lepidus on the Attalus site, and click on the entry links on the left side of each entry. The links take the form year/event, and the years in question are from 81 to 77, so the links are from 81/22 down to 77/9.
