Sister for Barnaby…

From your list I like Marla and Mabel.

Have you considered Fern/Fearne? It's not over used but seems similar to some of your suggestions.

Lots of lovely names- my favourites from the list are Iris, Elva, Delphine & Aster!

Our dog's name is Xanthe. The number of people who see it written down and don't know how to pronounce it, or hear it said and don't know how to spell it, is huge. It seems to be a less well known name than we expected. This may not bother you but thought I'd just mention it.

I see you have Marla on your list. It's not a name I've heard of before but it's rather nice. Or how about Mara? Or Meredith? Barnaby is a fabulous name!

I really like the name Barnaby and many from your list.

Love, love, love:
Stella (I also like Starr)
Frida
Cecily
Gabriella
Marigold

Not in a million years:
Dillon
Sydney
Allegra
Anouk
Bluebell
Fleur (sounds bleughh)
Delphine (ok if you're French, otherwise not)
Ever
Nola
Pandora
Xanthe

Barnaby & Gabriella is lovely.
I suggest:

Alice
Georgina
Caitlin
Clara
Catriona
Paige
Viola

I like Marigold Goldie

Stella - no
Dillon - no, not as good as Barnaby and wrong vibe, doesn't 'go'
Paloma - very pretty
Elva - sounds like vulva
Alva - sounds like vulva
Sydney - see comments for Dillon
Nancy - cool
Stevie - no, too nickname-y, not much to it
Frida - gorgeous
Anaise - it's spelled Anais, and as a teen she'd probably get called Anus. Much to my dismay, as I loved it too, but decided not to go for it for my daughter's sake! Teens are mean.
Allegra - lovely, classy, goes well with Barnaby
Mabel - cute and trendy
Anouk - cool
Anoushka - lovely
Aster - no, see comments for Dillon and Sydney
Aurora/Rory - a bit overdone now
Bluebell - a bit quirky, but a beautiful sound. Ive often wondered why this wasn't a more popular name as it ticks all the boxes. I think i am surprising myself by liking it.
Cecily - lovely and goes perfectly with Barnaby
Clover - pretty, but a bit cow-like
Fleur - i liked it until someone on Mumsnet said it sounds like someone being sick
Flora - love it and goes perfectly
Cosima - don't like it at all, no real reason why though.
Delphine - Donkey
Etta - becoming another Evie/Ava type name
Effie - love it as a nickname!
Mila - NO! So boring and overdone.
Evangeline - lovely and classy
Ever - what?
Nola - no
Gabriella/Gigi - very nice, classy
Iris - beautiful but getting popular
Maeve - see comments for Iris
Marigold/Goldie - no yuck
Marla - no yuck
Marlowe - nice sound but very different vibe to Barnaby! Id be really surprised to hear them as siblings
Uma - boring
Pandora - not very nice
Robin - nah
Romilly - reminds me of Rommel
Vivienne/Vivi - it's fine.
Xanthe - it's fine

Paloma, Frida, Allegra, Anoushka, Cecily, Flora. These to me are all perfect.

How about Tabitha?

From your list:

Barnaby and Stella
Barnaby and Maeve

Suggestions:

Barnaby and Kate
Barnaby and Melia
Barnaby and Amali
Barnaby and Katya

Louisa
Hannah
Emily
Alexandra
Lia
Claire

Mabel or Pandora

Stella - like
Dillon - awful
Paloma - not keen
Elva - baby eel
Alva - see Elva
Sydney - Sidonie is better
Nancy - ok
Stevie - ok
Frida - ok
Anaise - did you mean Anaïs?
Allegra - like
Mabel - ok
Anouk - ok
Anoushka - dated
Aster - not keen
Aurora/Rory - Too many Rs - Wowy or Vovy or Owowa/Ovova
Bluebell - no
Cecily - ok
Clover - no
Fleur - ok
Flora - like
Cosima - like
Delphine - ok
Etta - Ate a what?
Effie - Effin awful
Mila - no
Evangeline - no
Ever - Never
Nola - no
Gabriella/Gigi - gee-gee? No. Gabrielle a bit 1970s
Iris - ok
Maeve - no
Marigold/Goldie - no
Marla - no
Marlowe - no
Uma - ok
Pandora - no
Robin - no
Romilly - no
Vivienne/Vivi - no
Xanthe - ok

I really like Barnaby, but only like a few on your list. Some of them are dreadful

Nola 💖

Top 5:
Sydney
Fleur
Mila (As in Mee-La. Don’t like My-La)
Romilly
Xanthe

Absolute NO to:
Bluebell
Clover
Ever
Pandora