Congratulations 
Your children’s names are gorgeous!
Looking at your boys list I think [name_m]Finbar[/name_m], [name_m]Gideon[/name_m] + [name_m]Sampson[/name_m] are the best match. [name_m]Finlo[/name_m] + [name_m]Sholto[/name_m] are lovely however feel a little matchy with Jag0 due to that shared O sound.
[name_m]Finbar[/name_m] is a fun [name_m]Irish[/name_m] saints name that has the whimsy feel off Jag0. You can envision these two boys running on a pebbled beach on a windy day giggling with tide lapping at their feet. With their wise sister watching on smiling to herself.
[name_m]Gideon[/name_m] is such a handsome biblical name that feels strong and has the same unexpected feel of Jag0 + V3rity. I think [name_m]Gideon[/name_m] feels the most cohesive with your sibling set she has the O of Jag0 whilst having biblical ties to V3rity. He’s a favourite of mine and I love him so much. Jag0, V3rity & [name_m]Gideon[/name_m] is such a gorgeous sibling set.
[name_m]Sampson[/name_m] is another fab biblical name. He feels strong, well rounded, unexpected and handsome. I love the meaning ‘sun’ which could lead to the joyous nickname [name_f]Sunny[/name_f]. I do prefer the spelling [name_m]Samson[/name_m] just because I find the spelling more intuitive.
[name_f]My[/name_f] favourite is [name_m]Gideon[/name_m] 
Suggestions: [name_m]Elwood[/name_m], [name_m]Solomon[/name_m], [name_m]Penrose[/name_m], [name_m]Evren[/name_m], [name_m]Ziggy[/name_m], [name_m]Ozias[/name_m], [name_m]Ambrose[/name_m], [name_m]Tobin[/name_m], [name_m]Pascoe[/name_m], [name_m]Rafferty[/name_m], [name_m]Ives[/name_m],
[name_m]Emrys[/name_m], [name_m]Lorcan[/name_m], [name_m]Casimir[/name_m], [name_m]Abraham[/name_m], [name_m]Moses[/name_m], [name_m]Dorian[/name_m],
[name_m]Malachi[/name_m], [name_m]Simeon[/name_m], [name_m]Rupert[/name_m] + [name_m]Lowell[/name_m]
Regarding your girl names I absolutely love all these choices however with your kiddos names I love [name_f]Oonagh[/name_f], [name_f]Rosemary[/name_f] + [name_f]Marigold[/name_f]. I’m not keen on [name_f]Jemima[/name_f] with your sibling set due to the repeated starting initial of J it’s a bit matchy. I ideally I like children having their own initial.
[name_f]Oonagh[/name_f] ~ she’s fabulous choice that has that quirky off the beaten track feel. [name_f]Oonagh[/name_f] provides similar imagery [name_m]Finbar[/name_m] she has that wind swept pebbled beach image attached. I do prefer the more streamlined [name_f]Oona[/name_f] I find this spelling more attractive.
[name_f]Rosemary[/name_f] ~ such a lovely name that feels warm, nostalgic and elegant. [name_f]Rosemary[/name_f] has gorgeous connotations with the sea and roses that really appeals to me. [name_f]My[/name_f] only gripe is that both V3rity + [name_f]Rosemary[/name_f] have that y ending so do not feel as individualistic. V3rity + [name_f]Rosemary[/name_f] are very classic and do leave Jag0 on his own a little.
[name_f]Marigold[/name_f] ~ this is my favourite option for your sibling set! [name_f]Marigold[/name_f] is bright, summery and energetic she sounds beautiful with Jag0 + V3rity so cohesive. I love that she has her own individual sound and feel yet has the same whimsy magic off Jag0 + V3rity. [name_f]Lovely[/name_f] sibling set.
[name_f]My[/name_f] favourite is [name_f]Marigold[/name_f] 
Suggestions: [name_f]Enya[/name_f], [name_f]Ottilie[/name_f], [name_f]Imogen[/name_f], [name_f]Magnolia[/name_f], [name_f]Elspeth[/name_f], [name_f]Cordelia[/name_f], [name_f]Euphemia[/name_f], [name_f]Cerys[/name_f], [name_f]Laurel[/name_f], [name_f]Tabitha[/name_f], [name_f]Ione[/name_f], [name_f]Niamh[/name_f], [name_f]Noemi[/name_f], [name_f]Amabel[/name_f], [name_f]Greta[/name_f], [name_f]Heidi[/name_f], [name_f]Loretta[/name_f], [name_f]Winsome[/name_f], [name_f]Clemency[/name_f] + [name_f]Anouk[/name_f]
[name_f]Hope[/name_f] this helps
Good luck!