Maybe [name_m]Donovan[/name_m] [name_m]Alexander[/name_m] to avoid copying?
[name_f][/name_f]For brothers, I would probably go with [name_m]Donovan[/name_m] and [name_m]Dietrich[/name_m] if following the same initial letter. If not, maybe [name_m]Quillan[/name_m], [name_m]Ivan[/name_m], and [name_m]Linwood[/name_m].
[name_f][/name_f]For sisters, I would probably go with [name_f]Caroline[/name_f] and [name_f]Cecelia[/name_f] if following the same initial letter. If not, maybe [name_f]Vanessa[/name_f], [name_f]Giselle[/name_f], and [name_f]Dana[/name_f].
[name_f][/name_f]For middles without knowing what style you’re looking for, maybe:
[name_f][/name_f][name_m]Damien[/name_m] [name_m]Kerrick[/name_m]
[name_f][/name_f][name_m]Damien[/name_m] [name_m]Nathaniel[/name_m]
[name_f][/name_f][name_m]Damien[/name_m] [name_m]Lionel[/name_m]
[name_f][/name_f][name_m]Dominic[/name_m] [name_m]Oliver[/name_m]
[name_f][/name_f][name_m]Dominic[/name_m] [name_m]James[/name_m]
[name_f][/name_f][name_m]Dominic[/name_m] [name_m]Aurelian[/name_m]
[name_f][/name_f][name_f]Claire[/name_f] [name_f]Eliana[/name_f]
[name_f][/name_f][name_f]Claire[/name_f] [name_f]Jada[/name_f]
[name_f][/name_f][name_f]Claire[/name_f] [name_f]Penelope[/name_f]
[name_f][/name_f][name_m]Other[/name_m] than [name_f]Claire[/name_f] which is too common for me, I think [name_m]Damien[/name_m] and [name_m]Dominic[/name_m] both strike that balance of “not too common but well-known enough to be pronounced without issue.” They’re also strong and a bit moody IMO.
[name_f][/name_f][name_f]Claire[/name_f] is classic and connotates talent, competence, and sweetness to me.