Please help me with a sibling name to go with Theo!

[WhyTheHeckMe]

I'm 25 weeks pregnant and we have dc1 who is called Theo (not Theodore)
Really stuck on names. We loved theo as it was (in our opinion) not chavy but not weird. Not into "out there" names.
The only 2 names me and dh have agreed on are Oliver and Olivia! We've not found out the sex.
We like these names but they're both so common.
Any other suggestions?
It's harder for us because he has 9 cousins that are all boys so a few we like were taken already! Thanks

Olive if you like Olivia but wanted something less common but still use the nn Liv

Roman
Dash
Jenson
Hadley
Barney (Barnaby)
Oscar

Reuben / Robyn

Alicia
Ophelia
Leah
Jasmine
Rosalie

Alastair
Benjamin
Christopher (nn could be Kit)
Joshua
Otto

Otis
Hamish
Leo
Rupert

Orla
Elise
Amelia
Alice

Zoe
Luke
Alex
Dylan
Eliza
Summer

Jude

Phoebe
Rufus
Clara
Monty

Theo and James
Theo and Rex
Theo and Leon

Theo and Abigail
Theo and Joanna
Theo and Harriet

Jacob
Alexander
Toby
George

Arabella
Freya
Violet
Charlotte

Alexa
Sadie
Katie

Harry
Freddie
Joseph

The Theo I know has a sibling called Ethan.
Theo and Ezekiel (zeke)
Theo and Xander (Alexander)

Theo and Vienna
Theo and Imogen
Theo and verity

Alexander
Arthur
Hamish
Hector
Dexter
Oscar
Jasper

Sophie/Sophia

Lily
Sadie
Georgina
Matilda
Piper
Violet

All the Theo’s I know have brothers called Mac

Max

Theo and Xander
Theo and Solomon
Theo and Benjamin
Theo and Caleb

Theo and Beatrice
Theo and Minnie
Theo and Livvie
Theo and Betsy

Thanks so much for your suggestions it's really useful!

We have come up with a list now that we are quite happy with. What's your opinions on these?

Theo and Oliver
Theo and Joseph

Theo and Olivia
Theo and Harriet
Theo and Eva
Theof and Imogen

Theo and Oliver and Theo and Imogen are my fave from your list

Thanks 185ff you're the exact same as dh then :)