I love [name_f]Cleo[/name_f] but it does feel a bit matchy with [name_f]Cora[/name_f], especially if you call her [name_u]Coco[/name_u] as your username suggests.
I’m going to vote for [name_f]Zoie[/name_f]. It matches Cora’s length and blend of sweetness and spunkiness, although I think I’d prefer either the [name_u]Zoe[/name_u] or [name_f]Zoey[/name_f] spelling as they seem a little more intuitive to pronounce to me. [name_f]Zoie[/name_f] always makes me think “ZWAH”, to rhyme with the [name_u]French[/name_u] word “joie”.
[name_f]Fiona[/name_f] is lovely too, an unexpected but traditional choice. You can’t go wrong here!
[name_f]My[/name_f] favourite is [name_f]Cleo[/name_f], but I much prefer [name_f]Fiona[/name_f] with [name_f]Cora[/name_f]. I like [name_f]Fiona[/name_f] [name_f]Juliet[/name_f].
(sorry off topic but @katinka thanks for the clarification on [name_f]Joie[/name_f], I have a [name_f]Joie[/name_f] car seat and pushchair and never knew how to pronounce it!)