I think Coco could work - having a middle name that also started with the "ko" sound would make that a cute option actually. I prefer Delia or Deely for nicknames myself.
I REALLY like Cordelia Kitty Rosamund. It's classy, spunky, and fun. I like June and Beatrice too, but Kitty just can't be beat in terms of charming quirkiness.
Cordelia Rosamund CleoCordelia June MeredithCordelia Cora BeatriceCordelia Bess RosamundCordelia Blanche RosamundCordelia Ivy Beatrice, Cordelia Ivy RosamundCordelia Maude BeatriceCordelia Olive Rosamund