First, maybe we should consider some names that complement [name_f]Olivia[/name_f]- not too matchy, but not a complete style contrast! Here are a few suggestions:
[name_f]Victoria[/name_f]- both are four syllables and share the “v” sound- she could be [name_u]Vic[/name_u], [name_f]Vicky[/name_f] or [name_f]Tori[/name_f] to her friends and [name_f]Vivi[/name_f] to her sister?
[name_f]Eleanor[/name_f]- both begin in a vowel and have similar sounds. [name_f]Eleanor[/name_f] could be [name_f]Ellie[/name_f]/[name_f]Ella[/name_f]/[name_f]Elle[/name_f] to her friends and [name_f]Nora[/name_f] to her sister, or the other way around.
[name_f]Florence[/name_f]- I like that this is nickname rich- she might be [name_f]Flo[/name_f] to her friends and [name_f]Florrie[/name_f], [name_f]Flossie[/name_f] or [name_f]Floss[/name_f] to her sister.
[name_f]Beatrix[/name_f]- This is one of my favourite names! It gives you the very different nicknames [name_f]Bea[/name_f] and [name_f]Trixie[/name_f].
[name_f]Matilda[/name_f]- I know real siblings called [name_f]Olivia[/name_f] and [name_f]Matilda[/name_f]. She could be [name_u]Mat[/name_u] or [name_u]Mattie[/name_u] to her friends, and [name_f]Tilly[/name_f] or [name_f]Tilda[/name_f] to her sister.
Some more ideas:
[name_f]Caroline[/name_f]: [name_f]Carrie[/name_f], [name_f]Cara[/name_f]
[name_f]Amelia[/name_f]: [name_f]Amy[/name_f], [name_f]Mia[/name_f], [name_f]Melia[/name_f], [name_f]Lia[/name_f]
[name_f]Emilia[/name_f]: [name_f]Emmie[/name_f], [name_f]Mia[/name_f], [name_f]Millie[/name_f], [name_f]Mila[/name_f]
[name_f]Katrina[/name_f]: [name_f]Kat[/name_f], [name_f]Kate[/name_f], [name_f]Trina[/name_f]
[name_f]Delilah[/name_f]: [name_f]Dee[/name_f], [name_f]Lila[/name_f]/[name_f]Lilah[/name_f]
[name_f]Gabriella[/name_f]: [name_u]Gabby[/name_u], [name_f]Ella[/name_f]
[name_f]Millicent[/name_f]: [name_f]Millie[/name_f], [name_f]Milla[/name_f]
[name_f]Violet[/name_f]: [name_f]Vi[/name_f], [name_f]Lettie[/name_f]
[name_f]Scarlett[/name_f]: [name_f]Carly[/name_f], [name_f]Lettie[/name_f]
[name_f]Christina[/name_f]: [name_f]Chrissie[/name_f], [name_u]Chris[/name_u], [name_f]Tina[/name_f]
[name_f]Genevieve[/name_f]: [name_f]Gen[/name_f]/[name_f]Jen[/name_f], [name_f]Ginny[/name_f], [name_f]Vivi[/name_f]
[name_f]Rosalind[/name_f]: [name_f]Rose[/name_f], [name_f]Rosie[/name_f], [name_f]Lindy[/name_f]
[name_f]Daniella[/name_f]: [name_u]Dani[/name_u], [name_f]Ella[/name_f]
[name_f]Tallulah[/name_f]: [name_u]Tally[/name_u], [name_f]Lula[/name_f]
[name_f]Natalia[/name_f]: [name_u]Nat[/name_u], [name_f]Talia[/name_f]
[name_f]Winifred[/name_f]: [name_f]Winnie[/name_f], [name_u]Freddie[/name_u], [name_f]Freda[/name_f]
[name_f]Harriet[/name_f]: [name_f]Hattie[/name_f], [name_f]Etta[/name_f], [name_f]Ettie[/name_f]
[name_f]Anneliese[/name_f]: [name_f]Anne[/name_f], [name_f]Annie[/name_f], [name_u]Lisa[/name_u]
[name_f]Magdalena[/name_f]: [name_f]Maggie[/name_f], [name_f]Maddy[/name_f], [name_f]Lena[/name_f]
[name_f]Alexandra[/name_f]: [name_u]Alex[/name_u], [name_f]Alexa[/name_f], [name_u]Lexie[/name_u]
[name_f]Cordelia[/name_f]: [name_f]Cora[/name_f], [name_f]Dee[/name_f], [name_f]Delia[/name_f]