SOLVED. Girl in Atlantis YA-Midgrade novel [s]

[Melani]

I'm looking for a book about a girl, possibly a princess (she's at least a noble), in Atlantis just before it sinks. She learns that she's from the stars right near the end and there's this ritual thing they do to make sure they make it off the island. I think she may have had star tatoos/birthmarks on her wrist.

I read it in the late 80's. I got it from one of those Scholastic book sellers. The cover had the main character on it in a blue dress, she was standing straight looking up at the sky.

I want to say the word 'Star' was in the tittle, but every search I've had for 'Atlantis' and 'Star' hasn't given me the book I want.

[Tab]

Melani, do you remember any other fantasy/scifi elements? Like dragons, witches, time travel, etc?

Do you remember any other characters: family, friends, sidekicks, villains?

Part of a series?

[Andria]

Maybe Skyborn?

[Melani]

That's it. Thank you so much