What a fun sibling set!
[name_f][/name_f]Maybe you would like…
[name_f][/name_f][name_f]Cressida[/name_f] (Cress, Sid)
[name_f][/name_f][name_f]Melusine[/name_f] (Mel, [name_f]Lu[/name_f], [name_f]Lulu[/name_f], or Lucy)
[name_f][/name_f][name_f]Rosalind[/name_f] (Ro, [name_f]Rosie[/name_f], [name_f]Roz[/name_f], [name_f]Lindy[/name_f], [name_m]Sal[/name_m], Sally)
[name_f][/name_f][name_f]Guinevere[/name_f] (Guin, [name_m]Nev[/name_m], [name_f]Vera[/name_f], Ev, [name_f]Evvy[/name_f], Gwennie)
[name_f][/name_f][name_f]Saskia[/name_f] (Sass, Saski, Kiki)
[name_f][/name_f][name_f]Dulcinea[/name_f] (Dulcie)
[name_f][/name_f][name_f]Iolanthe[/name_f] (Io, Lani)
[name_f][/name_f][name_f]Belphoebe[/name_f] (Bel, [name_f]Phoebe[/name_f], Pheebs, Bebe)
[name_f][/name_f][name_f]Amaryllis[/name_f] (Amy, [name_f]Mary[/name_f], [name_f]Mari[/name_f], [name_f]Lissy[/name_f], Ama)
[name_f][/name_f][name_f]Olympia[/name_f] (Ollie, Pia)
[name_f][/name_f][name_f]Philippa[/name_f] (Pip, [name_f]Pippa[/name_f], Filly)
[name_f][/name_f][name_f]Sunniva[/name_f] (Sunny, Vivi)
[name_f][/name_f][name_f]Romola[/name_f] (Romy/Romi, Mo)
[name_f][/name_f][name_f]Romilly[/name_f] (Romy/Romi, [name_f]Ro[/name_f], Milly)
[name_f][/name_f][name_f]Idonea[/name_f] (Indie/Indy, Nea)
Not sure where you live – I tried to go with generally more unusual choices, but some (like [name_f]Romilly[/name_f] or Philippa) are significantly more popular if you’re in the UK versus in the US where they’re practically unheard of.