Let's try this again...
Sorry, y'all. My computer is acting up. Hopefully it'll work for me this time.
Sibling's names are Sophia Kristine, Landon Scott, and Ava Alexandra. Mom is stuck on Scarlett and Dad is stuck on Ivy. They both love Olivia, but fear it may cause friction with a family member if they use it. Other suggestions are also welcome! They're wanting to stay classic for the first name and they really enjoy romantic names.
AH this is a toughie! How much friction would using Olivia cause? Because really, a name is just a name, but if someone else is totally stuck on it, don't use it. However if it's not too big a deal, pick the name you both love! Auraya is beautiful! I prefer Scarlett to Ivy, but both are beautiful, especially with Auraya. I don't like Alessandra, but that's the only one I dislike. Really, you can't go wrong with any of those names, thye are all beautiful.
It seems a little strange (for me) to use Alessandra when big sister is Alexandra. Then again, it could be nice. I would need to think about it more.
Of the first names, I think I really like Olivia best with the existing siblings. Since it's a Top 5 most popular name with Sophia and Ava, it really seems made for the sibset. Scarlett feels harsh next to the softness of Sophia and Ava. I don't know if I would use Ivy with Ava, as they share similar sounds...
This is difficult. But if it were me, I would probably use Olivia Juliet.
Any suggestions for other possible first names?
I voted for Ivy Juliet because I think it has the best flow. Olivia would be the "predictable" choice with sisters named Sophia and Ava. I'm not a fan of Scarlett. Here are some other suggestions.
Isabella/Isabel - maybe too safe?
I accidentally voted before I even got to read all the names! Take off one for Scarlett Alessandra and give it to Olivia Juliet. It is classic, beautiful, and equally as popular as your other girl names. I agree with dovah that Scarlett seems a little harsh next to Ava, Sophia and Landon, and Ivy is too close in sound to Ava.
Isla or Lily instead of Ivy
Charlotte or Audrey instead of Scarlett
Alexa or Lillian instead of Olivia
I really love Isla Juliet and Alexa Juliet. Good luck to the parents!