So . . . I’m not expecting, but I like to be prepared!
What would you name another sibling to [name]Jacob[/name], [name]Colin[/name], and [name]Maxwell[/name] (nn [name]Max[/name])? First names only, as we use family names for middles.
Boy or girl. I have some ideas but my favorites don’t work for a variety of reasons.
[name]Jacob[/name], [name]Colin[/name], [name]Max[/name], and…
[name]Lucy[/name], [name]Alice[/name], or [name]Eliza[/name]
[name]Arthur[/name], [name]Andrew[/name], or [name]Henry[/name]
[name]Ruby[/name]
[name]Abigail[/name]
[name]Holly[/name] (I [name]Holly[/name] would be nice)
[name]Olivia[/name]
[name]Willow[/name]
[name]Zoe[/name]
[name]Oliver[/name]
[name]Noah[/name]
[name]Ethan[/name] (I think this would be lovely)
[name]Zachary[/name]
[name]Isaac[/name]
My first idea was [name]Samuel[/name]. I think [name]Jacob[/name], [name]Colin[/name], [name]Max[/name], and [name]Sam[/name]/[name]Samuel[/name] would be adorable together! I think something like [name]Lucy[/name] or [name]Isabella[/name] (popular though it is!) would be lovely with your boys. I also like the idea of something like [name]Clara[/name]/[name]Cara[/name]/[name]Cora[/name], [name]Hannah[/name], [name]Julia[/name], [name]Elise[/name], [name]Penelope[/name], or [name]Annabel[/name].
Good luck!
I agree that [name]Samuel[/name] would make a great sibling… also, [name]Isaac[/name], [name]Leo[/name], [name]Drew[/name], [name]Charlie[/name], [name]Toby[/name] or [name]Nicholas[/name] maybe.
You guys do a great job!
For those who mentioned [name]Lucy[/name]–it’s one of my favs, but I have a friend/neighbor who has a [name]Max[/name] and a [name]Lucy[/name], and while I feel comfortable copying one name, two is too many. Unless I move. 
Other names I like:
[name]Cora[/name]
[name]Clara[/name]
[name]Alice[/name]
[name]Olivia[/name] (but I kind of like [name]Olive[/name] better–thoughts?)
[name]Hannah[/name]
[name]Holly[/name] (but I think I like [name]Molly[/name] a little more)
[name]Willow[/name] is lovely. I haven’t ever thought of that one.
[name]Oliver[/name] (love it! but since [name]Colin[/name] is often called [name]Collie[/name], and I know [name]Oliver[/name] would get called [name]Ollie[/name] . . . )
[name]Noah[/name] (but DH doesn’t love it)
[name]Issac[/name]
[name]Charlie[/name] (so cute!)
[name]Sam[/name] (that does fit nicely with our sib set, doesn’t it?)
I also have a crush on [name]Griffin[/name], but DH isn’t sure. [name]Do[/name] you think that name fits?