Help suggest names for Arthur & Niamh's sibling

[AvalancheRoses]

I'm nearing 3rd trimester and DH and I have still not even managed a shortlist of names.

We have two children

Arthur Lawrence Gray
Niamh Elizabeth Rose

There is one name we think is ok is Theia for a girl, but even then we're both on the fence about it. I suppose we're looking for traditional but slightly unusual names.

We're staying team green, so girl and boy names would be appreciated.

Jemima
Marianne
Phoebe

Tobias
Rupert
George

Girls:

Emilia
Esme
Maeve
Heidi
Carina
Orla
Eliza

Boys:

Finley
Jasper
Theodore
Alexander (nn Xander)
Aaran
Archie

all the best and congratulations!

Guinevere (Ginny)

Lancelot
Maximilian

Frederick
Gregory
Nathaniel
Vincent
Simeon
Maximilian
Joseph
Roderick

Tabitha
Lilian
Virginia
Henrietta
Margot
Susannah
Georgina
Flora
Mabel

Tristan
Iseult

Cressida
Druscilla
Lavinia
Phaedra

Marmaduke
Lincoln
Kingsley
Horatio

How is Theia pronounced? Like Thea?

Phoebe goes lovely with your other DC's names.

Other suggestions:
Abigail
Hermoine
Theodora
Ava
Caitlin

Fredrick
George
Theodore
Daniel
Isaac

I was going to suggest Iseult. Also Saoirse, Caoimhe.

Finnian, Fingal.

Anya
Romy
Eden
Soreya
Estelle
Lois
Loretta
Elayna
Xanthe
Sienna
Marcia
Lucia
Millicent

Lysander
Xavier
Hudson
Harris
Landon
Remy
Marcus
Vincent
Jenson
Ellis
Eli

Fergus?
Ciara?

Magnus
Genevieve

Isolda
Miriam
Harriet

Fergus
Sidney
Francis

I'd stay away from another 'th' name as you already have Arthur.

Phoebe
Erin
Aoife

Lachlan
James
Otto

Iseult
Nancy
Sadhbh

Finbar
Alistair
John

Meredith
Letitia
Verity
Pandora
Maude
Pippa
Flora
Fleur

Hamish
Angus
Donal
Stanley
Gideon
Wilfred

Jasmine
Leah
Eloise
Corinne
Cassia
Emmeline
Pearl
Robyn
Verena
Imogen
Merryn
Greta

Saul
Alistair
Julian
Marcus
Xander
Raymond
Connor
Vincent
Sebastian
Miles
Elliott
Dylan