I'm struggling to find a name combination for our little one on the way that sings to me as much as our daughter's name - Ariadne Mira.
The combinations we have so far agreed on are:
Boy - Ender Leonid
Girl - Petra Alcyone (al-SIE-ə-nee)
Ender has been a longtime favourite for us. Petra I am adoring because it is a variant of Peter, and my deceased father's name was Peter. We also have an astronomy/space middle name theme going on if you can't tell 
Other names on our list:
Cordelia, Gretchen, Persephone, Cressida, Capella.
Kepler, Altair, Rigel.
Any thoughts on our top choices so far, or other suggestions we could throw on the table?
TIA!
Re: Sibling for Ariadne
I think they both would sound fine with your daughter's name, and I don't mind either of them.
OP - love Petra and the family meaning. Like all of your other girl names, but Capella is my least favorite. Makes me think of music and singing a capella. Which might be what you're going for, I don't know.
I'm not even familiar with the boy names, but think Kepler would be the one least likely to be confused with other names.
Edit: also love how Leonid sounds. Reminds me of the meteor shower every August. (For me, that's a good thing. Always around my birthday)
**siggy warning**
Current Age 35, DH 33
Married 9/2011
BFP 8/2012, Miscarried 9/2012
BFP 9/2012, DS 6/2013
BFP 6/2014, Miscarried 7/2014
BFP 7/2014, DD 4/2015
I actually think your top choices are the best ones, although Petra's middle name will be hard for people at the DMV and things like that. But that isn't every day, so not the worst thing. I really like that Petra is a variant of your dad's name.
Petra Calliope
Petra Penelope
Petra Thais
Petra Helene
Not into Ender but it's just bc its not my style!
EDD for #1: 3/19/17