Just a note...for some meds like antibiotics...penicillin, sulfonamide powder, and some other meds you need look no further than your local farm stores. They sell many of these in bulk and the quality is very high. Of course you need some background in medicine to be able to correctly use them but it isn't rocket science and a usable dosage chart for the meds you have should be kept with them.
If you do add meds to your kit make sure you are aware of some of the side effects, with Sulfonamide for example you have to keep the patient well hydrated or severe kidney damage can occur. And of course there can be adverse reactions to many drugs. I would actively recruit a Doctor into joining your group or if that is not possible an EMT or nurse. Always good to have a medic on hand in emergencies.