Help naming baby girl

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We're looking for a girls name, preferably 4 syllables, that shortens nicely to a nn, to match her brother, Sebastian (Seb). Open to ideas as we are stuck in a rut and baby is 2 weeks old! Middle name will be May. Thanks in advance 😊

I really like Alexandra but I'm not keen on Alex for a nn, would love Alexa but.. you know

Margarita nn Rita, Meg or Maggie
Elizabeth nn Liz, Bess

Alexandra nn Sasha

Evangeline
Octavia
Lillian

Francesca
Annabel
Rosanna
Josephine
Genevieve

Olivia nn Liv
Ophelia nn Phi
Amelia nn Mil ?
Emelia nn Em

Can only think of 4, Ive gone blank

Catherine
Susannah
Josephine

Cordelia

Persephone

Calypso

These were the first 4 syllable names that sprang to mind:
Isabella
Evangeline
Georgiana

Victoria
Anastasia
Elizabeth
Penelope
Isabella
Felicity
Georgiana

Amelia
Angelica
Ariadne
Antigone
Aurelia
Astoria
Calliope
Cecilia
Eliana
Elizabeth
Evelina
Eulalia
Isabella
Indiana
Liliana
Lavinia
Octavia
Penelope
Persephone
Tatiana

Evangeline
Seraphina

Clementine

Genevieve
Angelica
Juliana
Seraphina
Cecilia
Leonora

Hermione (Mimi if you need a nickname)
Clementine (Clemmy)

Elizabeth

Or I know 2 Sebastian and Elodie sibling sets

Arabella
Magdalena
Mariella
Frederica
Boadicea
Calliope
Persephone
Henrietta
Scheherazade
Cleopatra

Immediately thought of Veronica to go with Sebastian

Why not Alexis?

Marianna? Seraphina?

My favourite at the moment is Alessandra nickname Ally or Sasha.

Margaretta/Margareta - both international variants pronounced margaRET-a, with little bit drawn RET part
Cordelia
Veronica
Felicity nn Lissy or Fliss

Because of Sadlers Wells?!

OP, I thought of Virginia (Ginny), Vanessa (Ness) and Adelaide. Not four syllables though.