Ok, I found your boys list way easier than your girls. That said i like:
Sullivan (it's not my faveriot but it has girlie nn possibilities Liv, Soolie, Livy, Sunny)
Hero (guilty pleasure for me)
Can't warm too:
Lennon (Beatle mania)
Flannery (flan as a nn? Hmmm)
Sweeney (Sweeney Todd)
Avocet (reminds me of avocado)
Good luck! Compromise is tough!
Adah Katherine- Wow, a great Southerny name!
Edith Katherine "Edie"- A wonderfully vintage name.
Cecily Katherine "Kit"- Love! So classic, but unique.
Afton Mary- I know a girl by this name. Truly adorable.
Louisa Katherine "Lou"- A classic name that you know will age well.
Genevieve Mary "Evie"- A bit common, but nice.
Maude Katherine "Maudie"- Love it except for the "Harold and Maude" thing...
Saffron Mary "Saffy"- One of my favs!
Zinnia Katherine "Zinn"- Like this a lot.
Forsythia Mary- Very unique and interesting.
Camellia Mary (I like Millie, he likes Cam...sigh)- a sweet spot name... not unknown, and not too common.
Lilac Mary- very nice
Hero Katherine- Love, reminds me of Much Ado!
Sweeney Katherine reminds me of weeny and Sweeney Todd... not the best. I can't see Rue aging well. Guthrie is like a gruff old man. Poppy reminds me of papi, poopy, and opium. Sullivan is just too popular for boys.
it seems many of your names are just names a girl WOULD NOT WANT TO HAVE. think of how a little girl as well as a woman would feel calling herself some of these names
favs & best suggestions are in bold:
Adah Katherine - pronounced like Ada? stick to this spelling if used, i say dont, no flow
Monroe Katherine - becoming a popular unisex name. plus reminds me of Marilyn and i cant understand the worlds love of her. yes she died young but she didnt seem like the best person.
Sinclair Mary - sounds like a nun
Edith Katherine "Edie" - just ok, becoming a popular 'old lady' resurgence name
Sullivan Mary "Liv" - not a unisex name that really works for a girl, its like the other unisex names are too popular so you were stuck with this one because no one uses it...for good reason.
Frances Katherine "Franny" - no girl wants this name
Lennon Mary - to many famous people
Poppy Katherine - no flow, Poppy just seems to nicknamey
Cecily Katherine "Kit" - love, good flow, Kit is cute
Afton Mary - sound like a truly all male name, no girl wants to grow up with it
Flannery Katherine - no girl wants this name
Nerissa Mary - reminds me of narcissistic and yet i prefer the name Narcissa.
Euphemia Mary "Effie" - horrible sounding name
Louisa Katherine "Lou" - just ok, Lou isnt that great but i guess its been done before
Genevieve Mary "Evie" - popular but classical.
Maude Katherine "Maudie" - try Maudlin or another variation. again no girl wants this name and very few can pull it off
Saffron Mary "Saffy" - dont force nicknames, some names just dont create good ones. just call her Saffron
Avocet Katherine - no femininity at all
Zinnia Katherine "Zinn" - a flower name that seems picked because all the others are more popular, for good reason - again
Sparrow Katherine - TRENDY
Forsythia Mary - seems like an over flourished name
Greer Katherine - to me this name is in the same category as Sloane - somehow they do work for a girl and feel feminine on them
Guthrie Katherine - no girl wants this name
Camellia Mary - reminds me of the English adulteress
Vesper Katherine - TRENDY
Rue Katherine - TRENDY, HUNGER GAMES
Piper Katherine - okay, has a its 'been done already' vibe
Romilly Katherine "Romy" or "Milly" - go with Romy or Milly instead or other origins of those nicknames, together this name doesnt flow within itself at all, it clashes
Lilac Mary - not horrible, the obvious choice for those trying to get away from Violet and Lavander
Remedios Mary "Remy" - REMEDIAL? DONT USE THIS. plus its a definiete boys name, no girl in here at all, not even Remy
Sweeney Katherine - Todd? THE DEMON BARBER OF FLEET STREET? again if you were a girl would you want this name? NO
Hero Katherine - you are trying waaay to hard
Alba Katherine - Jessica Alba. but not the worst on your list
Ophelia Katherine - pretty popular
Narrowed Down To:
Cecily - try Thessaly
Romy - actually a diminutive of Rosemary > Rosalind,Rosalyn, Rosalie, Rosario
Millie - Matilda, Mila, Melisende
Major Suggestions: SLOANE may help find a compromise between you and your husband & MAUDLIN gives a major face lift while still keeping an olden charm
Katherine Alternatives - plenty of none crazy spelling choices to pick from and a very internationals that deserve a look
-sometimes all you need is a -lina or -rina to help the flow of a name
Cataline, Catarine, Cathaleen, Catharina, Cathelina, Cathleen, Katherina, Katarina, Katelle, Katchen
-again sometimes an -en or -anna really helps lol
Marie, Mair, Mal (Leo's wife in Inception had this name! sounded more like Maul but i liked it) Maren, Mariam, Marian (Robin Hood), Mariana, Maridel, Marla, Marlo, Marissa, Maurene, Merrill, Millie, Molly, Moira - Wendy Darling's middle
Adah Katherine - Very cute. I prefer Ada without the H, but if the H makes your husband feel better about Ada, then use the H.
Monroe Katherine - Katherine Monroe is better.
Sinclair Mary - Cute and different! I like it. A little preppy.
Edith Katherine "Edie" - Edie is very cute, but I have a hard time imagining an 8 year old named Edith enjoying her name.
Sullivan Mary "Liv" - Very creative, but not cute. She would probably get picked on.
Frances Katherine "Franny" - Fran would be a better nickname.
Lennon Mary - Cute
Poppy Katherine - Very cute and preppy
Cecily Katherine "Kit" - I like it a lot
Afton Mary - No way. ever.
Flannery Katherine - No
Nerissa Mary - Kind of cute
Euphemia Mary "Effie" - No
Louisa Katherine "Lou" - Lovely
Genevieve Mary "Evie" - Very usable and likeable
Maude Katherine "Maudie" - I prefer Maeve
Saffron Mary "Saffy" - Very very cute and different
Avocet Katherine - No
Zinnia Katherine "Zinn" - Cute
Sparrow Katherine - I like it, but it's hard to imagine a Dr. Sparrow Katherine
Forsythia Mary - No
Greer Katherine - never been a fan of Greer
Guthrie Katherine - NO
Camellia Mary (I like Millie, he likes Cam...sigh). - You call her Millie and he can call her Cam
Vesper Katherine - no
Rue Katherine - CUTE
Piper Katherine - Kind of over done
Romilly Katherine "Romy" or "Milly" - VERY much like
Lilac Mary - cute
Remedios Mary "Remy" - no
Sweeney Katherine - NO NO NO
Hero Katherine - LOVE IT, but she would get picked on
Alba Katherine - Like it
These have wonderful flow. My faves are bolded. The trouble with using a surname with Mary as a mn is that often the combos are better switched around (Mary Sinclair and Mary Lennon look and sound better to me). FYI- Harper is already the TRENDIEST name (mostly for girls).
Louisa Katherine "Lou"