[Bozos of Bones]

The problem here is the sorcerer is the prime and only spellcaster so that needs versatility which the sorecerer lacks. So you need to emulate it. You will be needing lots of direct damage spells(Fireball, Skull Trap, Mordenkainen's Force Missles...)and plenty of buffs. Don't concern yourself with protection spells accept for the sorc, meaning take some low-level protectionspells but pass on the higher level ones like the ultra-costly impervius Sanctity of Mind. Stop somewhere at Trollish Fortitude. But the final choice of role for the sorc is your call. You have two(one and a half) healers and clerics can dish out some mean spells(Harm, Glyph of Warding, Holy Word) as can druids.