I personally think [name_f]Eliza[/name_f] is more sophisticated/literary than [name_f]Cleo[/name_f] but that’s up to you if it matters or not.
[name_f][/name_f]I also personally think [name_f]Cleo[/name_f] [name_f]Claire[/name_f] and [name_f]Keira[/name_f] [name_f]Claire[/name_f] are both too much. Trying to say the last two together is a bit of a mouthful.
[name_f][/name_f]Maybe [name_f]Tessa[/name_f] [name_f]Cleo[/name_f] or [name_f]Tessa[/name_f] [name_f]Claire[/name_f]? I think that might match better[name_f][/name_f].
[name_f][/name_f]Names I think pair well with big sis’s name / [name_f]Claire[/name_f] or [name_f]Cleo[/name_f] as a middle:
[name_f][/name_f][name_f]Alice[/name_f] [name_f]Claire[/name_f] / [name_f]Cleo[/name_f]
[name_f][/name_f][name_f]Violet[/name_f] [name_f]Claire[/name_f]
[name_f][/name_f][name_f]Virginia[/name_f] [name_f]Claire[/name_f]
[name_f][/name_f][name_f]Estelle[/name_f] [name_f]Claire[/name_f] / [name_f]Cleo[/name_f]
[name_f][/name_f][name_f]Rosella[/name_f] [name_f]Claire[/name_f]
[name_f][/name_f][name_f]Fern[/name_f] [name_f]Cleo[/name_f]
[name_f][/name_f][name_f]Tiffany[/name_f] [name_f]Claire[/name_f]
[name_f][/name_f][name_f]Norah[/name_f] [name_f]Claire[/name_f] / [name_f]Cleo[/name_f]
[name_f][/name_f]A few wildcards that switch things around for your consideration:
[name_f][/name_f][name_f]Clara[/name_f] [name_f]Abigail[/name_f]
[name_f][/name_f][name_f]Cecelia[/name_f] [name_f]Jane[/name_f] nn “Cece”
[name_f][/name_f][name_f]Tess[/name_f] [name_f]Cecelia[/name_f]
[name_f][/name_f]Hopefully these help! 