I’ve discussed this passage before (Orberg’s adapted (I think) Livy). I know what it means but am not sure how the grammar works in the clause beginning ‘…, fratris filiae Reae Silviae,…’
Trying to translate literally, '…when he selected Rea Silvia his brother’s daughter as a Vestal virgin he removed, through perpetual viginity, hope of issue.
What is the case of Reae Silviae? : it’s either dative or genitive but I can’t justify either. Shouldn’t it be ablative - he denied her. I can’t see that adimo, adimere takes dative. Does it take dative becauase he’s doing this to her, because she’s an indirect object with the direct object being ‘spes’?
What’s ‘eam’ doing? This is feminine accusative. It’s simply a pronoun object of ‘legisset’ meaning ‘her’ right?
Rheae Silviae – most likely dative, the complement of the pre-verb ad- in adimit ("he took away from Rhea Silvia the hope of issue by [condemning her to] perpetual virginity . . . ").
It might also be analyzed as genitive, depending on virginitate (“by the perpetual virginity of Rhea Silvia, he removed the hope of issue”), but dative seems more natural, though perhaps counterintuitive to English speakers who translate this verb as “take away from”.
“What’s ‘eam’ doing? This is feminine accusative. It’s simply a pronoun object of ‘legisset’ meaning ‘her’ right?”
Just an extra note about OLD vs L&S dictionaries. Here’s a case where OLD is much better than L&S in its entry for “adimo”, with so many examples “(w. dat)”, illustrating “aliquid alicui adimere”. Hoc addo. En explicationis exemplum ubi OLD dictionarium illud de L&S praestat, quod usus casûs dativi creber ad verbum adimere serviendum planè in OLD praebetur.