So, having used up our favourite names on our first two children, #3 took a while to be chosen. Now in considering #4 we’re totally stumped! [name_m]Zebedee[/name_m], [name_f]Elsbeth[/name_f], [name_f]Tabitha[/name_f] and…go!
If it helps they are
[name_m]Zebedee[/name_m] [name_m]Tom[/name_m]
[name_f]Elsbeth[/name_f] [name_f]Beatrix[/name_f]
[name_f]Tabitha[/name_f] [name_f]Hope[/name_f]
I like [name_m]Boaz[/name_m] (we started with a Z, I like the idea of ending with a Z). I also like [name_u]Joby[/name_u] [name_m]Obadiah[/name_m], [name_f]Posey[/name_f], my hubby likes [name_f]Hepzibah[/name_f] (too mean?) Any ideas of combos or help for fresh thinking? I like uncommon but not totally out there names. We now know 5 [name_f]Tabitha[/name_f]'s so would like something a bit less popular. We also seem to have chosen names with ‘b’ in them. Not compulsary this time but certainly in my thinking.
Generally trying to keep with the b theme somewhere in the name and not too common;
[name_m]Caleb[/name_m]
[name_m]Balthazar[/name_m] (B and Z link back to your first)
[name_u]Blaize[/name_u] (B and Z link back to your first)
[name_m]Ebeneezer[/name_m]
[name_m]Abner[/name_m]
[name_m]Able[/name_m]
Denby (Inverted the last to main sounds from zeBeDee - DenBy)
[name_m]Sebastian[/name_m] - or just [name_m]Bastian[/name_m]???
[name_m]Bazil[/name_m]
girls names with a b…drawing quite a blank
[name_f]Zenobia[/name_f] - feels more your style - b and z link back to your first
[name_u]Zion[/name_u] (no b link but again feels more your style and link back to firstborn)
[name_f]Abbeline[/name_f]
[name_f]Hepzibah[/name_f] is nms but if its yours go for it - although I would be wary that the other girls have much more ‘user friendly’ / known but unusual names and this could cause friction later on. Also [name_u]Joby[/name_u] - would that be pronounced [name_m]Jobe[/name_m] or Jobby? I would expect some pronciation issues, also I personally wouldn’t match it with your current sibset but again if you love it then go for it!
[name_f]Hope[/name_f] that gives a few ideas 
I love love [name_f]Elsbeth[/name_f] (see my signature). [name_m]How[/name_m] exciting to add a 4th child. Other names you may like are.
Girls
[name_f]Bathsheba[/name_f]
[name_f]Phoebe[/name_f]
[name_f]Alberta[/name_f]
[name_f]Fabiana[/name_f]
Jubliee
[name_f]Isolde[/name_f]
[name_f]Mabel[/name_f]
[name_f]Isla[/name_f]
[name_f]Mehitabel[/name_f] ([name_f]Mabel[/name_f])
[name_f]Genevieve[/name_f]
[name_f]Sybill[/name_f]
[name_f]Isadora[/name_f]
[name_f]Liberty[/name_f] ( [name_f]Libby[/name_f])
[name_f]Guinevere[/name_f]
[name_f]Roberta[/name_f]
[name_f]Imogen[/name_f]
[name_f]Adelaide[/name_f]
Eliabel
Boys
[name_m]Zebediah[/name_m]
[name_m]Judah[/name_m]
[name_m]Cuthbert[/name_m]
[name_m]Webster[/name_m]
[name_m]Gabriel[/name_m]
[name_m]Archibald[/name_m] ([name_m]Archie[/name_m])
[name_m]Colbert[/name_m]
[name_m]Gibson[/name_m]
[name_m]Tobias[/name_m]
[name_m]Fabian[/name_m]
[name_m]Gideon[/name_m]
-
B-
[name_m]Aloysius[/name_m]
[name_m]Ignatius[/name_m]
[name_m]Hezekiah[/name_m]
[name_m]Leonidas[/name_m]
[name_m]Garrick[/name_m]
[name_m]Osiris[/name_m]
[name_u]Zephyr[/name_u] -
G-
[name_f]Octavia[/name_f]
[name_f]Cordelia[/name_f]
[name_f]Ophelia[/name_f]
[name_f]Emmeline[/name_f]
[name_f]Elora[/name_f]
Evandne
[name_f]Ariadne[/name_f]
[name_f]Cosima[/name_f]
[name_f]Seraphina[/name_f]
[name_f]Evangeline[/name_f]
[name_f]Mathilde[/name_f]
[name_f]Guinevere[/name_f] “[name_f]Vera[/name_f]”
[name_f]Bridgette[/name_f]
[name_f]Minerva[/name_f]
[name_f]Aurelia[/name_f]
[name_f]Tallulah[/name_f]
[name_f]Clementine[/name_f]
[name_f]Catriona[/name_f]
[name_f]Briony[/name_f]
[name_f]Cressida[/name_f]
[name_f]Rosamond[/name_f]
[name_f]Primrose[/name_f]
[name_f]Wilhelmina[/name_f] “[name_f]Minnie[/name_f]”
[name_f]Ramona[/name_f] “[name_u]Romy[/name_u]”
[name_f]Romilly[/name_f]
[name_f]Cecilia[/name_f]
[name_f]Cecily[/name_f]
[name_f]Amelie[/name_f]
[name_f]Mabel[/name_f]
[name_f]Maude[/name_f]
[name_f]Desdemona[/name_f]
Zebedee, Elsbeth, Tabitha and…
Girls
Matilda
Adeline/Adelaide
Christabel
Romilly
Sybil
Boys
Barnaby
Amos
Leander
Magnus
Phineas
I feel like the names you and your S.O choose are names that are considered unusual, but most people have heard before.
[name_f]Keziah[/name_f] would be my choice for a girl, I think it would go wonderfully with your other children’s names. And [name_f]Keziah[/name_f] [name_f]Posey[/name_f] would be so sweet!
For boys, I think [name_m]Boaz[/name_m] is a great choice. I also suggest:
[name_m]Balthazar[/name_m]
[name_u]Azariah[/name_u]
[name_m]Ephraim[/name_m]
[name_m]Lazarus[/name_m]
[name_u]Jericho[/name_u]
Good [name_m]Luck[/name_m]!
[name_m]Jubal[/name_m] (has same feel as [name_m]Zebedee[/name_m] and has b in it!)
[name_m]Welby[/name_m]
[name_u]Urban[/name_u]
[name_u]Zion[/name_u]
[name_m]Fritz[/name_m] (incorporates the z at the end)
[name_f]Mabel[/name_f]
I absolutely love the idea of [name_u]Joby[/name_u] [name_m]Obadiah[/name_m]! It’s my favorite of the ones you’re considering.