jillian - lily, ili, lia
rosemary - mary, mare, osie, emmy
juliet - etta, lia, ulie
jessica - essie, jj
charlotte - arlo, lottie, lolly, ari
elizabeth - libby, lia, abby, zaza, ethie
margaret - maggie, mari/mary, ari, etta
gwendolyn - dolly, enna, lyn
abigail - gail, bibi
julianna - anna, lia, annie, uli
isabel - bella, abby, isa
kevin - ev, vinny
patrick - rick(y), ati, trick
[name_f]Rosemary[/name_f] - [name_u]Romy[/name_u], [name_u]Rory[/name_u]
[name_f]Juliet[/name_f] - Jett/Jette
[name_f]Charlotte[/name_f] - [name_u]Otter[/name_u] or [name_u]Arlo[/name_u]
[name_f]Elizabeth[/name_f] - [name_u]Eli[/name_u], [name_f]Zibby[/name_f], [name_f]Bitsy[/name_f], Izzo
[name_f]Isabel[/name_f] - Izzo
[name_m]Patrick[/name_m] - [name_m]Patch[/name_m], Tricky
[name_f]Jillian[/name_f] — [name_u]Jae[/name_u] / [name_u]Jay[/name_u]
[name_f]Rosemary[/name_f] — [name_u]Romy[/name_u]
[name_f]Juliet[/name_f] — [name_f]Lettie[/name_f]
[name_f]Jessica[/name_f] — [name_u]Essa[/name_u] / [name_f]Essie[/name_f]
[name_f]Charlotte[/name_f] — Charlie/Lottie
[name_f]Elizabeth[/name_f] — Libby/Betty/Bess/Liza
[name_f]Margaret[/name_f] — [name_f]Maggie[/name_f], [name_f]Maisie[/name_f]
[name_f]Gwendolyn[/name_f] — [name_f]Gigi[/name_f]
[name_f]Abigail[/name_f] — [name_f]Gail[/name_f]
[name_f]Julianna[/name_f] — [name_f]Annie[/name_f], Jae/Jay
[name_f]Isabel[/name_f] — Is (Iz), [name_f]Belle[/name_f]
[name_m]Kevin[/name_m] — K (lol, this is a tough one!)
[name_m]Patrick[/name_m] — Rick/Ricky
[name_f]Jillian[/name_f] - [name_f]Jinny[/name_f], [name_f]Annie[/name_f], [name_m]Jam[/name_m], [name_f]Linny[/name_f]
[name_f]Rosemary[/name_f] - [name_u]Romy[/name_u], [name_u]Rue[/name_u], [name_u]Rory[/name_u], [name_u]Sam[/name_u], Marsie, [name_u]Royce[/name_u]
[name_f]Juliet[/name_f] - [name_f]Etta[/name_f], [name_u]Jet[/name_u], [name_f]Lia[/name_f], [name_u]July[/name_u], [name_f]Lettie[/name_f]
[name_f]Jessica[/name_f] - [name_f]Essie[/name_f], [name_u]Joss[/name_u], [name_u]Ice[/name_u], [name_u]Cass[/name_u]
[name_f]Charlotte[/name_f] - [name_f]Lottie[/name_f], [name_u]Kit[/name_u], [name_u]Arlo[/name_u], [name_f]Hattie[/name_f]
[name_f]Elizabeth[/name_f] - [name_f]Zibby[/name_f], Bizzy/Busy, [name_f]Etta[/name_f], [name_f]Lilibet[/name_f], [name_f]Libby[/name_f], [name_f]Lily[/name_f]
[name_f]Margaret[/name_f] - [name_u]Ari[/name_u], [name_f]Etta[/name_f], [name_u]Garnet[/name_u], [name_m]Argo[/name_m] (like the ship), Grem
[name_f]Gwendolyn[/name_f] - [name_f]Dolly[/name_f], [name_f]Wendy[/name_f], [name_f]Ginny[/name_f], [name_f]Glinda[/name_f], [name_u]Ollie[/name_u]
[name_f]Abigail[/name_f] - [name_m]Gibby[/name_m], [name_u]Gabby[/name_u], [name_f]Libby[/name_f]
[name_f]Julianna[/name_f] - [name_f]Leni[/name_f], [name_f]Annie[/name_f]
[name_f]Isabel[/name_f] - [name_f]Sally[/name_f], [name_u]Sable[/name_u], Sabby, [name_f]Elsa[/name_f], [name_f]Lizzy[/name_f]
[name_m]Kevin[/name_m] - [name_m]Ken[/name_m], [name_u]Nev[/name_u]
[name_m]Patrick[/name_m] - [name_m]Patch[/name_m], [name_f]Trixie[/name_f], [name_u]Pax[/name_u]
I’m sure many of these have been said already 
Got it!
Jillian-Jan
Rosemary-Romy
Juliet-Lettie
Jessica-Sassy
Charlotte-Lottie, [name_u]Chase[/name_u]
Elizabeth-Elsie, [name_f]Eliza[/name_f], [name_f]Bess[/name_f], [name_f]Bette[/name_f], [name_f]Tess[/name_f]
Margaret-Molly, [name_f]Maisy[/name_f], [name_f]Maggie[/name_f], [name_f]Peggy[/name_f], [name_f]Gerty[/name_f], [name_f]Margot[/name_f]
Gwendolyn-Winnie, [name_f]Gigi[/name_f]
Abigail-Billie
Julianna-Annie
Isabel-Ibbi
Kevin-Kit
Patrick-Patch
[name_f]Hope[/name_f] this helps. 
[name_f]Jillian[/name_f]: I would say [name_f]Lia[/name_f] or even [name_f]Lily[/name_f] for a stretch
[name_f]Rosemary[/name_f]: [name_f]Mary[/name_f] or [name_u]Marie[/name_u]. I would even say [name_u]Esme[/name_u] for a stretch
[name_f]Juliet[/name_f]: [name_u]Lee[/name_u] comes to mind. [name_f]Ettie[/name_f] too
[name_f]Jessica[/name_f]: [name_f]Sisi[/name_f] comes to mind. Also [name_f]Essie[/name_f] too
[name_f]Charlotte[/name_f]: [name_f]Charlotte[/name_f] is easy. [name_u]Charlie[/name_u] or [name_f]Lottie[/name_f]. [name_u]Arlo[/name_u] if you want a stretch
[name_f]Elizabeth[/name_f]: I have a million! [name_f]Eliza[/name_f], [name_f]Elise[/name_f], [name_f]Elsie[/name_f], [name_f]Lizzy[/name_f], [name_f]Betty[/name_f], and [name_f]Elsa[/name_f] come to mind
[name_f]Margaret[/name_f]: [name_f]Maggie[/name_f], [name_f]Marge[/name_f], Ret, [name_f]Margie[/name_f]
[name_f]Gwendolyn[/name_f]: [name_u]Lyn[/name_u], Gwenie, [name_f]Dolly[/name_f], [name_f]Winnie[/name_f]
[name_f]Abigail[/name_f]: [name_f]Gail[/name_f] comes to mind quickly
[name_f]Julianna[/name_f]: [name_f]Annie[/name_f], [name_f]Anna[/name_f], [name_f]Lia[/name_f], [name_f]Lianna[/name_f]
[name_f]Isabel[/name_f]: [name_f]Belle[/name_f], [name_f]Bella[/name_f], [name_u]Isa[/name_u]
[name_m]Kevin[/name_m]: Only one that comes to mind is Vinnie/Vin
[name_m]Patrick[/name_m]: I recently came across [name_u]Pax[/name_u] as a stretchy nickname. Also [name_u]Ricky[/name_u], [name_m]Rick[/name_m], Trick, and [name_f]Patty[/name_f] work
Jillian—Lilly, [name_f]Annie[/name_f], [name_f]Illa[/name_f]
Rosemary—Mary, [name_f]Rosette[/name_f]
[name_f]Juliet[/name_f] – [name_f]Lettie[/name_f], [name_f]Ettie[/name_f]
Jessica– Sicca
[name_f]Charlotte[/name_f] —Lotta, [name_f]Lottie[/name_f]
[name_f]Elizabeth[/name_f] — [name_f]Eliza[/name_f], [name_f]Bess[/name_f], [name_f]Ella[/name_f], [name_f]Liza[/name_f], [name_f]Elise[/name_f], [name_f]Elsie[/name_f], [name_f]Elsa[/name_f]
[name_f]Margaret[/name_f]— [name_f]Maggie[/name_f], [name_f]Greta[/name_f], [name_f]Mara[/name_f], [name_f]Mari[/name_f], [name_f]Retta[/name_f]
Gwendolyn– [name_f]Dolly[/name_f], Wend, [name_f]Lynnie[/name_f]
Abigail– [name_f]Gaila[/name_f], [name_f]Ally[/name_f], [name_u]Abba[/name_u]
[name_f]Julianna[/name_f] —Anna, [name_f]Annie[/name_f], [name_f]Liana[/name_f], [name_f]Julia[/name_f]
Isabel—Belle, [name_f]Bella[/name_f], [name_u]Issa[/name_u]
[name_m]Kevin[/name_m] —Vin, [name_u]Vinny[/name_u], [name_f]Evvie[/name_f]
[name_m]Patrick[/name_m] —Rick, Trick