Help, we are stuck - we already have an Olivia, surname is a pretty common one, one syllable, beginning with C.
In no particular order:
Phoebe
Verity
Isobel/Isabel
Ottilie
Elodie
Saskia
Clementine (but probably not, due to alliteration).
It does bug me slightly how popular Olivia is, but it was our favourite at the time.
Any thoughts/alternative suggestions on the above welcome?!