How do [name_m]Carlos[/name_m] and [name_f]Stella[/name_f] sound as a sibset? What about [name_m]Carlos[/name_m] and [name_f]Isabella[/name_f] or [name_m]Carlos[/name_m] and [name_f]Danielle[/name_f]?
I like [name_m]Carlos[/name_m] & [name_f]Stella[/name_f] the best! I think your other combos work too, but [name_f]Stella[/name_f] gives [name_m]Carlos[/name_m] a really bright, stylish and energetic vibe! I love both names 
I like [name_m]Carlos[/name_m] and [name_f]Stella[/name_f]! Both have a bit of flair to them!
[name_m]Carlos[/name_m] and [name_f]Isabella[/name_f] would be my next pick
[name_m]Carlos[/name_m] and [name_f]Stella[/name_f] are great! I like it better than any of the alternatives too.
They’re quite different styles to me, but I think they work. I think [name_m]Carlos[/name_m] and [name_f]Isabella[/name_f] (or Isabela) would be a better match.
I like [name_m]Carlos[/name_m] and [name_f]Stella[/name_f]! They fit together well. I like Carols and [name_f]Stella[/name_f] the best out of your options. [name_m]Carlos[/name_m] and [name_f]Isabella[/name_f] second best