I also like the suggestion of Farrah AND keeping the B-C-E-F theme, very cute! If you wanted to keep that 'theme' going...
I would say Diane...an ancient classic that's a now-new choice, fits in with the number of syllables, and is the right letter in the scheme...B, C, ?, E...
I love the ideas of Farrah and Laurel. I think those are right on track with the name advice I would give!
I love Laurel too! Also Willow, Winslow, Vera, Veda, Gemma, Georgia, Sari, Raina, Rowan, Shiloh, Tabitha, Tallula, Daisy, Dahlia, Dalia, Goldie (Marigold), Frances, Juliet, Nora, Marlowe,