My husband and I adore the name Beatrix is we ever have a girl (3rd child). Our first child is named Felix and our second child is Theodore.
Do you think it matters that the last two letters of Beatrix and Felix are the same?
Our Felix is usually called Flix or Felix and we anticipate that Beatrix would be called Bee or Bé (my grandmother's nickname). That plus they'll probably only live together for 12 or so years (he would be 7-8 years older than her).
I wouldn't. But then, I am fairly obsessed about not alliterating or repeating sounds within names or across siblings. My DD is Flora Elisabeth Zoë - note that I did not call her Elizabeth because I thought that would be overdoing the "z"s.
Felix and Theodore are both lovely names; how about something a bit more feminine than Beatrix for your hypothetical DD? I think more femininity would complement Felix and Theodore better.
Octavia - great if you can pull it off Tabitha - like Cordelia - like Ursula Callista Aurelia - love love love! Dh vetoed for me Saffron Juniper - heard this recently and growing on me Paloma - beautiful, but weird if you have no Spanish links Claudia - love, anothe veto by dh Calliope - least favourite
I like Octavia, Aurelia and Paloma best from your list
Octavia - like Tabitha - cat's name Cordelia - don't like Ursula - dislike Callista - not keen Aurelia - lovely Saffron - no Juniper - gin Paloma - like, and nice meaning Claudia - not keen Calliope - not keen
Octavia - NO, it's dour Tabitha - OK Cordelia - LOVE Ursula - NO Callista - Not sure Aurelia - No, reminds me of areola Saffron - OK, but a bit dated and weak Juniper - No, poncey Paloma - Lovely Claudia - No, too precious and trying to be glam Calliope - No, sounds like a greek island or an Italian dish