The Green Hermit
Hero
Ditto.
But I'm quite happy punishing the crap out of them if they don't recruit NPCs to fill the gaps in their lineup, once they realize those gaps exist. (and four levels in, they ought to have figured these things out by now even if they're all brand new to it; but if they haven't maybe the DM might want to let them rescue a Fighter-4 NPC prisoner somewhere who's willing to join up if the party equip her.......)
This is really only the third scenario in the campaign. Four levels or not, the dragon hatchery is pretty early in.