Ex utraque civitate frequentes Romam migraverunt, parentes maxime ac fratres raptarum. From each city they departed to Rome, especially parents and brothers of the ravished women.
I’m having trouble making frequentes fit into this sentence. Frequent parents and brothers?
Frequens means ‘crowded’. The sense is that people go there with much frequency. From there you get the sense of “many”, being equivalent to “celeber” (from which we have celebrity, with a similiar etymological jump: a celebrated place, or a celebrity, is someone or some place which many people visit). So your sentence just means that ‘many people migrated to Rome.’