[name_f]Marina[/name_f] is my favorite pick for a sister for [name_f]Anastasia[/name_f]. I just haven’t gotten any positive feedback on it, [name_m]IRL[/name_m] or online! I like the other names on our list well enough ([name_f]Isadora[/name_f], [name_f]Cordelia[/name_f], [name_f]Christiana[/name_f], [name_f]Seraphina[/name_f], [name_f]Celestia[/name_f]/maybe [name_f]Celeste[/name_f]), but they either seem a little too out there or too matchy with big sis. So, please share your honest thoughts on [name_f]Marina[/name_f]. Good, bad, blah?
[name_f]Marina[/name_f] - good, mermaid, pretty, sounds normal, strong, yet girly, between frilly and down-to-earth, which is good thing.
Honestly, I think [name_f]Marina[/name_f] is adorable. I love it’s charm and uniqueness. All the other names on your list are cute too and would be cute with [name_f]Anastasia[/name_f]. Good luck! 
I love [name_f]Marina[/name_f]. Beautiful meaning and sound, [name_f]Marina[/name_f]'s perfect. I sincerely hope it being used more.
Very pretty.
It’s not matchy with [name_f]Anastasia[/name_f]; though it has a slightly similar vibe.
It has cute nn’s; love [name_f]Marnie[/name_f]!
Seems like a lovely option, despite not being super familiar. I suppose [name_f]Mariana[/name_f] would be the more familiar option.
My main connection is with [name_f]Marina[/name_f] Sirtis and of course with boat marinas (which are lovely)
I also like [name_f]Isadora[/name_f] a lot, though it’s more similar to [name_f]Anastasia[/name_f].
I like [name_f]Marina[/name_f], it has a really good sound. It’s quite popular in [name_f]Austria[/name_f] so people are quite familiar with the name here but it seems that the name is less familiar/popular in other countries.
I hate to be a [name_f]Debbie[/name_f] downer, but I am not a fan. It has a generic mermaid quality. I also think of a lake marina and fresh beat band. I think [name_f]Cordelia[/name_f] from your list is gorgeous!
I think [name_f]Marina[/name_f] is a very pretty choice! It makes for a very Eastern European sibset with [name_f]Anastasia[/name_f]. My only warning for the name [name_f]Marina[/name_f] is be certain that your surname isn’t the name of an actual marina in your area or nearby
I agree with this.
[name_f]Marina[/name_f] is lovely.
Okay I honestly adore [name_f]Marina[/name_f].
[name_f]Marina[/name_f] has this oceanic elegance which is just gorgeous. [name_f]Marina[/name_f] has this lovely wholesome vibe and feels very effortless. [name_f]Marina[/name_f] is a great choice conjuring up images of harbours, sea life, fisherman and a clear blue sea. Maybe a pebbled beach. It’s just delightful. So vibrant. [name_f]Anastasia[/name_f] teamed with [name_f]Marina[/name_f] isn’t a pairing I would have initially thought off but I think it works in a cool unique way, despite clashing in style.
I love this name and I think it goes well with [name_f]Anastasia[/name_f]
I love the name [name_f]Marina[/name_f]. I like the sound, the meaning, and all my associations with it are positive.
[name_f]Marina[/name_f] is terrific!