[name_m]Hi[/name_m] there.
[name_m]Even[/name_m] though [name_f]Martha[/name_f] or [name_u]Mattie[/name_u] are not really my style, I do find [name_f]Martha[/name_f] [name_u]Juniper[/name_u] nn [name_u]Mattie[/name_u] pretty adorable!
Here are my thoughts on your current lists:
Girls:
[name_f]Clementine[/name_f] [name_u]Love[/name_u] it! I think just [name_f]Clementine[/name_f] works, but also the nn [name_f]Cleo[/name_f] is cute. [name_f]Clementine[/name_f] nn [name_f]Minnie[/name_f] is nice too, but [name_f]Minnie[/name_f] & [name_u]Mattie[/name_u] may be too cheesy.
[name_f]Elizabeth[/name_f] w/ nicknames ([name_f]Betsy[/name_f], [name_f]Libby[/name_f], [name_f]Eliza[/name_f] or [name_f]Libby[/name_f])-I love [name_f]Eliza[/name_f]. I think that [name_f]Betsy[/name_f] works best w/[name_u]Mattie[/name_u] though. [name_f]Tess[/name_f] would also be good.
[name_f]Sarah[/name_f] or [name_f]Sadie[/name_f] -[name_f]Sarah[/name_f] nn [name_f]Sadie[/name_f] is perfect w/[name_f]Martha[/name_f] nn [name_u]Mattie[/name_u]. Also [name_f]Susanna[/name_f] nn [name_f]Sadie[/name_f] (or [name_f]Sally[/name_f]).
[name_f]Margot[/name_f] -Nice, but obviously too close to [name_f]Martha[/name_f].
[name_f]Olive[/name_f]-I love the nn [name_f]Livy[/name_f].
[name_f]Ella[/name_f]-Pretty, but a different style from [name_f]Martha[/name_f] in my opinion. It also seems nick-namey to me.
[name_f]Caroline[/name_f]-I like it okay too, but agree that [name_f]Carrie[/name_f] is kind of meh.
[name_u]June[/name_u]-Ooh, [name_f]Junie[/name_f] & [name_u]Mattie[/name_u] are perfect!
[name_f]Beatrice[/name_f]-So sweet. [name_u]Mattie[/name_u] & [name_f]Bea[/name_f]/[name_f]Bess[/name_f]/[name_f]Bette[/name_f]…or you could even do [name_f]Betsy[/name_f] here.
[name_f]Adele[/name_f]-This is fine. It doesn’t sparkle, & [name_u]Mattie[/name_u] & [name_f]Addie[/name_f] rhyme.
[name_f]Josephine[/name_f]-I love it. What do you think of the nn [name_f]Posy[/name_f]?
[name_f]Claire[/name_f]-This is fine, but not super exciting.
Girl suggestions:
[name_f]Beatrix[/name_f]/[name_f]Trixie[/name_f]
[name_f]Coraline[/name_f]/[name_f]Cora[/name_f]
[name_f]Cornelia[/name_f]/[name_f]Nellie[/name_f]
[name_f]Dorothy[/name_f]/[name_f]Daisy[/name_f]
[name_u]Eloise[/name_u]/[name_f]Lulu[/name_f]
[name_f]Eleanor[/name_f]/[name_f]Nellie[/name_f]
[name_f]Frances[/name_f]/[name_f]Francie[/name_f]/[name_f]Franny[/name_f]
[name_f]Georgia[/name_f]/[name_u]Georgie[/name_u]
[name_f]Georgina[/name_f]/[name_u]Georgie[/name_u]
[name_f]Kathleen[/name_f]/[name_u]Kit[/name_u]/[name_f]Kitty[/name_f]
[name_f]Lucille[/name_f]/[name_f]Lucy[/name_f]/[name_f]Lulu[/name_f]
[name_f]Phoebe[/name_f]
[name_f]Penelope[/name_f]/[name_u]Penny[/name_u]/[name_f]Polly[/name_f]/[name_f]Nellie[/name_f]…I really like [name_u]Mattie[/name_u] & [name_f]Polly[/name_f].
[name_f]Virginia[/name_f]/[name_f]Ginny[/name_f]
[name_f]Wilhelmina[/name_f]/[name_f]Willa[/name_f]/[name_f]Winnie[/name_f]
Boys:
[name_u]August[/name_u]-So handsome. [name_m]Just[/name_m] the right amount of gentle manliness. [name_u]Gus[/name_u] or [name_m]Augie[/name_m] are adorable nns too. Or [name_m]Ace[/name_m].
[name_m]Declan[/name_m]-I love this one too. It wouldn’t be my first pick w/[name_f]Martha[/name_f], but a nice name none the less.
[name_m]Theodore[/name_m] -Cute, but getting so popular. Lots of great nn options.
[name_m]Julian[/name_m]-[name_u]Love[/name_u] it! Not my first pick w/[name_u]Mattie[/name_u], but it is on my top three list.
[name_m]Charles[/name_m] nn [name_u]Charlie[/name_u]-This is nice. I love [name_u]Charlie[/name_u].
[name_m]Leander[/name_m] nn [name_u]Lee[/name_u] or [name_m]Zander[/name_m] -This is not my style, but okay.
[name_m]Jacob[/name_m]-Great name, but way popular.
[name_m]Oliver[/name_m]-Same as above, really.
[name_u]Elias[/name_u]-This is handsome. [name_m]Eli[/name_m] is quite popular, but this is my favorite [name_m]Eli[/name_m] name.
[name_m]Samuel[/name_m]/[name_m]Samson[/name_m]-I love [name_m]Samuel[/name_m]. [name_m]Samson[/name_m] is good too, & less common. [name_u]Mattie[/name_u] & [name_u]Sam[/name_u] work.
[name_m]Abel[/name_m] -Very cool & different.
[name_u]Raleigh[/name_u] -Seems a little out of left field. Maybe nice for a mn.
Boy suggestions:
Alistiar/[name_m]Ace[/name_m]/[name_u]Alfie[/name_u]
[name_m]Alfred[/name_m]/[name_m]Ace[/name_m]/[name_u]Alfie[/name_u]/[name_u]Freddie[/name_u]
[name_u]Asa[/name_u]/[name_m]Ace[/name_m]
[name_m]Bernard[/name_m]/[name_u]Bernie[/name_u]/[name_m]Ben[/name_m]/[name_m]Benny[/name_m]
[name_m]Barnaby[/name_m]/[name_m]Barney[/name_m]/[name_m]Barnes[/name_m]
[name_m]Beckett[/name_m]/[name_u]Kit[/name_u]
[name_m]Edward[/name_m]/[name_u]Teddy[/name_u]/[name_m]Ned[/name_m]
[name_u]Elliott[/name_u]
[name_m]George[/name_m]/[name_u]Georgie[/name_u]
[name_m]Hugo[/name_m]
[name_m]Hugh[/name_m]/[name_m]Hughie[/name_m]
[name_m]Harrison[/name_m]/[name_m]Harry[/name_m]/[name_m]Hank[/name_m]
[name_m]Knox[/name_m]
[name_m]Louis[/name_m]/[name_m]Louie[/name_m]
[name_m]Oscar[/name_m]
[name_m]Otis[/name_m]
[name_u]Owen[/name_u]
[name_m]Peter[/name_m]/[name_m]Pip[/name_m]
[name_m]Rafferty[/name_m]/[name_u]Rafe[/name_u]
[name_m]Thomas[/name_m]/[name_m]Tucker[/name_m]
[name_m]William[/name_m]/[name_u]Billy[/name_u]
[name_f]Hope[/name_f] this helps. 