First, some thoughts on the names you listed, then some suggestions ^^
[name]Juliette[/name]: I love this spelling as opposed to [name]Juliet[/name]. This is definitely classic and romantic, and sounds great with big sister [name]Mirabelle[/name].
[name]Evelyn[/name] - I like the name [name]Evelyn[/name], but I’m not sure it has that romantic feel for me in the same way [name]Mirabelle[/name] does. Might be a bit too trendy/popular? Also, not sure if you use a nn for your daughter, but [name]Mira[/name] and [name]Evie[/name] is quite cute ^^
[name]Amelia[/name]- Not the biggest fan of this, I immediately think [name]Amelia[/name] [name]Bedelia[/name]. I do like [name]Emilia[/name] though!
[name]Camelia[/name] - Nice alternative flower name, but I’m not the biggest fan personally. Reminds me of [name]Camilla[/name] and [name]Cornelia[/name]. Sounds like a grandmother name to me, and I don’t think it stands up to [name]Mirabelle[/name] in beauty or in terms of aging.
[name]Serena[/name] - I like this name, and it’s certainly romantic and fantastical. Reminds me of the anime [name]Sailor[/name] [name]Moon[/name] ^^
[name]Laurel[/name] - [name]One[/name] of my favorite L names! I think it sounds lovely with [name]Mirabelle[/name]! The mythological aspect of [name]Laurel[/name] ([name]Daphne[/name], who turns into a [name]Laurel[/name] tree) is incredibly romantic and classic!
[name]Lily[/name] as a middle name only - I like this for a middle name ^^ Definitely a classic name.
I also [name]ADORE[/name] [name]Genevieve[/name] and [name]Evangeline[/name]–they are two of my absolute favorites! A couple suggestions hopefully similar…
[name]Larissa[/name] - possible nickname [name]Lara[/name]. This was a character from Dr. [name]Zhivago[/name], and her tale is quite romantic ^^
[name]Vienna[/name] - place name, but I like this name as a sister for [name]Mirabelle[/name]
[name]Audrey[/name] - miss Hepburn was a timeless beauty, and so is her name ^^
[name]Eliora[/name] - means “god is my light,” again I like this with [name]Mirabelle[/name]
[name]Alouette[/name] - a possible French middle name? means [name]Lark[/name]
[name]Evelina[/name] - love [name]Evangeline[/name] and [name]Evelyn[/name]? Perhaps [name]Evelina[/name] is for you! Also [name]Evalina[/name]. This is another literary name from a romantic story of the same name. Possible nicknames include [name]Evie[/name], [name]Eva[/name], or [name]Lina[/name].
[name]Solana[/name] - I first saw this name in a movie, but I think [name]Solana[/name] sounds quite unique and feminine.
[name]Eleanora[/name] - I like this with [name]Mirabelle[/name]. Possible nicknames could be [name]Ellie[/name], [name]Nell[/name], [name]Nellie[/name], [name]Nora[/name], [name]Lana[/name], [name]Lora[/name], etc.
[name]Odette[/name] - another french name, possibly for the MN? [name]Odette[/name] is the white swan from swan lake
[name]Cosette[/name] - girl who finds love in [name]Les[/name] Miserables, french name
[name]Aveline[/name] - one of my favorite french names
[name]Annelise[/name] - suggested just for the spelling. avoids any um…unpleasant words in the middle of the name lol
[name]Cora[/name]/[name]Cordelia[/name] - [name]Cora[/name] is another name for [name]Persephone[/name], and her story is definitely classic and romantic. [name]Cordelia[/name] means daughter of the sea, which is romantic as well.
[name]Mignonette[/name] - preferably a mn choice, and I know it might be a bit “out there”, but I have a soft spot for [name]Mignonette[/name]. This is one of the middle names of [name]Mia[/name] in the princess diaries, as well as a classic name of European royalty. I think it literally means “[name]Little[/name] cutie” or something like that haha
I hope maybe I could help spark an idea for you, and either way, good luck naming your little one! I just love [name]Mirabelle[/name], and I’m sure whatever name you pick for her sister will be just as lovely ^^