[name_f]Blair[/name_f] and [name_f]Maeve[/name_f] do have slightly different vibes, but I don’t think that means they don’t work together. Your twins are very likely to have totally different personalities, so I think it’s appropriate to have one name be simple elegance while the other is spunky grace. They’re both strong, not overly frilly names which is why I do think they work together.
[name_f][/name_f][name_m]Henry[/name_m] sounds great with [name_m]Miles[/name_m], but I get your concern about popularity. [name_m]Emmett[/name_m] is always the name that comes to mind for me when I think about a brother to [name_m]Miles[/name_m]. [name_m]Miles[/name_m] [name_m]Robert[/name_m] and [name_m]Emmett[/name_m] [name_m]Henry[/name_m] are perfection in my opinion. 