[name]Isla[/name] christiana ( middle name is my mom) nickname iylie or christiane for middle
[name]Carys[/name] christiana(christiane)middle option
I like [name]Carys[/name]!
[name]Both[/name] are lovely… I prefer [name]Carys[/name], but [name]Isla[/name] works better w/the middle name. Congratulations!!
I prefer [name]Isla[/name]; [name]Carys[/name] is okay but it sounds a lot like [name]Karen[/name] to me.
I love [name]Isla[/name] Chistinana !!! and Iylie for a nn is adorable!
I have an [name]Isla[/name] so I am biased. I still love it. We call her Isles. Iylie is very cute!
My favorite from your choices is [name]Isla[/name]. It sounds more feminine to me. I think [name]Isla[/name] [name]Christiane[/name] is gorgeous!
I like [name]Carys[/name]! It sounds spunky and fun, and I love the meaning. [name]Isla[/name] looks great on paper, but (just my humble opinion) sounds really plain and dull when spoken. Reminds me of an octogenarian, too (I suppose because of its similarity to [name]Ida[/name]?).
Congratulations! [name]Hope[/name] you and baby girl are feeling well! [name]Both[/name] the names you are considering are so pretty, so she can’t lose. 
My favorite is [name]Carys[/name]. I think it is elegant and unusual, but still familiar and very wearable. In my opinion, it will age better than [name]Isla[/name].
[name]Carys[/name] [name]Christiane[/name].
[name]Carys[/name] Chistiane/a is absolutely beautiful! Good luck!
I would choose [name]Isla[/name] [name]Christiane[/name] (no ‘a’). Please post in the birth announcement section when you have decided on her name.
[name]Both[/name] are nice, but I vote for [name]Isla[/name]. You middle name choice is wonderful! Congratulations on your baby girl!!!
As other users have said both options are stunning but I have always seen [name]Carys[/name] as completely enchanting and I think it flows well with either of your middle options. Congrats on your baby girl!
I would go with [name]Isla[/name] [name]Christiane[/name].
[name]Carys[/name] is lovely but I personally don’t like alliteration.
my vote goes to [name]Carys[/name].
[name]Isla[/name] is too popular these days
I vote [name]Isla[/name].
[name]Isla[/name] [name]Christiane[/name] sounds best of the options.
I love [name]Carys[/name]. [name]Isla[/name] is very pretty too.
Maybe neither one is her name. Maybe that’s why you are having trouble deciding…
But out of the two names I like [name]Carys[/name] the best.
my vote would be for [name]Isla[/name] [name]Christiane[/name].