lemon's list "Lemon's Classic Picks for Girls" of 4 great name ideas: Gwendolen - Margaretta!

Lemon's Classic Picks for Girls

Gwendolen, an ancient Welsh favorite, retired decades ago in favor of the short form Gwen, but now, as in the case all across the naming board, the nickname has faded and the more distinguished original is up for reappraisal. Gwendolen means "white circle," probably alluding to an ancient moon goddess, and appears in both Welsh and English legend, once as a fairy with whom King Arthur fell in love and another as the wife of the wizard Merlin.
 Gwendolen is the name of principal characters in George Eliot's novel Daniel Deronda and in the Oscar Wilde play, The Importance of Being Earnest.
 An alternate spelling is Gwendolyn, as in Gwendolyn Brooks, the first African-American woman to win a Pulitzer prize for poetry. Gwendolyn, always the more popular spelling in the U.S. and the full name of the character Winnie Cooper on The Wonder Years is now at Number 514, having reached as high as 112 in the 1950's.

Gwendolen

Briony may be the variation and Bryony the original, but many parents will see this as the more authentic-feeling version of this attractive botanical name. Melodic and bright, it was once a Top 400 name in the UK back in the 90s but has since fallen out of favor, as has Bryony.
 
The name of a vine once used for medicinal purposes, Briony is derived from the Greek bryo meaning "to swell, sprout, grow", likely in reference to the plants ability to climb. As such, Briony isn't related to the similar sounding Brian, though it could nevertheless make an honor name for one.
 A literary choice, Briony appears in Ian McEwan's popular novel, Atonement, in which the young, imaginative Briony Tallis sets the plot in motion. In the screen adaptation, she was played by Saoirse Ronan, for which she received a Best Supporting Actress Oscar nomination.
 
In the most recent stats, no girls were called Briony (or Bryony) in the US, while in the UK, just over 30 babies were given the names collectively. With potential nicknames Bonny, Brie, or Bee, Briony could make an unexpected yet familiar option.

Briony

Adeline

Margaretta is an elaborate feminine variation of Margaret, which derives from the Greek word "margarites" meaning "pearl." This extended form adds a romantic, slightly European flair to the classic name. Margaretta has appeared throughout history, particularly in the 18th and 19th centuries, though it has always been less common than Margaret or its other variants like Marguerite or Margarita. The name has an elegant, vintage quality with its flowing four syllables and graceful ending. While never reaching high popularity rankings, Margaretta maintains an air of distinction and refinement, appealing to those who appreciate traditional names with a touch of uncommon sophistication.