Hmm... In that case, if you do make a "Halfling Witch" class, I reccomend making it an arcane or eldrich spellcaster. I mean, you were probably going that way already, but still: Giving each member of the class a different repertoire of known spells/ceremonies goes a long way toward making it feel like each halfling witch has his or her own circumstances and background explaining how he or she stumbled across forbidden magic.