Hmmm....

The challenge with Annabelle is I think you want to pick something for her sister that isn't too, "precious," or frilly, but you don't want something too plain-Jane either.

I love Ruby, Lucy, Clara, and Eloise. All of which have that storybook charm quality.

I like Rose, Rosemary, and Camille from your hubby's list which have a similar charm but seem more grounded than his other choices.

I would nix Corrina,Dalia,Daria,Delia,Elaine,Gabriella,Jacqueline,Jeanette,Leila,Martina,Maxine,Sabrina, Sienna,Simone,Sonia, and Stephanie, all of which seem the wrong sound/origin/ear to me. From yours, I would ax Abigail, Amelia,Carolina,Eliza,Elsa,Leora,Naomi,Talia, and Violet, for similar reasons.

Others

Georgia

Lorelei

Emmeline

Sophia or Isabelle would be nice, if you decide you don't mind popularity.

Of all your names combined, my favorite for a sister to Annabelle is Coraline.  Both 3 syllables, but not frilly and the nicknames Anna and Cora are great if the girls ever want them.  That said, I think most of the names on both lists are really quite nice.  Some other suggestions; Ginevra, Juliette, Lillian, Miranda, Theordora, Vanessa.

My favourites off your lists are:

Amelia, Eliza, Evelyn, Louisa, Violet, Coraline, Elaine, Martina, Simone, Stephanie

My suggestions would be:

Valerie
Lydia
Alessia (if you don't mind the double A - but you have Amelia on your list, so probably not)
Gemma
Rachel
Cosima
Carla/Carlie

Of your list I like Cecilia and Louisa. From his I'll pick Jacqueline and Rosemary. I think I agree with some of them being stylistically different like Simone, Stephanie, Elsa, and Abigail. Plus I'm not really a fan of reusing initials. So I think my favorite is Cecilia.

I too was going to propose Juliette.  I actually prefer it as Juliet, but the extra letters would match better with Annabelle.  

I'm probably oversimplifying, but looking at both your lists, it seems that your husband is sort of riffing off the very feminine/graceful vibe of Annabelle, whereas you are responding more to the classic/Victorian/unusual-but-not-wacky feel it has.

So, trying to reconcile the two, I come up with:

Lucinda

Felicity (or Felicia/Felice)

Verity

Penelope

Jessamine

Calista

Lavinia

From your existing list, the ones I'm most drawn to are: Carolina (but prefer Caroline), Cecilia, Clara, Evelyn, Lucia.  And I might tweak Leora to Leonora or Leonore for a better stylistic match to Annabelle.  I also like the suggestions of Georgia and Miranda.

Thanks all! Very helpful.  Cecilia and Lousia are two of my favorites too. And I really like the suggestion of Leonora. I don't know that I even really had heard of it before, but it's rising fast on my list.  By the way, for those of you who like Coraline, how would you pronounce it?  Is one way more standard than the other?

 A few of you pointed out that a number of names on my list like Naomi, Talia, Abigail, and Leora don't really seem to fit with Annabelle. You are probably right. They come from another naming style I'm drawn to which are Hebrew/Old Testament names. I might have to give up on that, especially since my husband isn't a particular fan. 

Your dilemma is similar to my dilemma with a few differences. I'm of the "classic" or "old-fashioned" (as my husband would say), while he very much like very femine, French "frou-frou" (as I called it--or "stuffy") names.

Emaline was a contender until my SIL snagged it (family name), and we ended up with Evangeline. Classic & old-fashioned feeling for me while still femine and "frou-frou" enough for him. :-) I have no idea what we will do if we have another girl. Emaline, Evangeline, Coraline, and Caroline seem to fit well with Annabelle to me. :-)

BTW--I adore most of the names on your list, and even some on your husband's list. :-)

I think previous posters are right-on as to the general feel of your and your husband's lists. Annabelle is flexible enough to fit with a variety of names, and what you choose for her sister will emphasize the shared qualities of both names. For a match, I'd look for something longish and flowing (Eva and Rose seem a bit short), not too fussy, without multiple "sharp" consonants. I'd also steer clear of "el" names (Eleanor, Gabrielle, etc.) for a more distinct sound. (Abigail, Amelia, Elaine and Evelyn are also a little close for my tastes.)

From your lists, my favorite matches in bold:

Abigail, Amelia, Carolina->Caroline, Cecilia, Clara, Eleanor, Eliza, Eloise, Elsa, Eva, Evelyn, Leora, Louisa, Lucia, Lucy, Naomi, Rosa, Ruby, Talia, Violet

Camille, Coraline, Corinna, Dalia, Daria, Delia, Elaine, Gabriella, Jacqueline, Jeanette, Josephine nn. Josie, Leila, Martina, Maxine, Rose, Rosemary, Sabrina, Sienna, Simone, Sonia, Stephanie

I like the suggestions of Juliette, Leonora, Lucinda and Lydia.

How about Alice/Alison, Charlotte, Madeleine, Marian, Tessa, Vivian/Vivienne?

How about Elisa?

Are you planning to have more children?  (Not to get too personal!) Keep in mind that if more children are in the plans, choosing a longer, VERY stylisticly-matched name to Annabelle might make you feel stuck with that style for baby girl #3 or 4 (should they appear).  Names like Eliza, Lucy, Ruby, Violet, and Rose match the sweetness of Annabelle without going overboard on fanciness.  

Of course, you may feel differently or may be done after two or may have only boys from here on out, so you may not want to leave out a favorite name because it's TOO matchy with Annabelle. 

I lov ethe name Annabelle. And Josephine is my first choice for a girl!