I think Scafool hit on the nearest thing to a solution. It's back to the cardboard sign concept: Work for Food. Trade labor and knowledge for admittance to the survival 'group'.
* That 'old witch' down the street knows wild foods and herbs.
* The engineer and the builder can come up with small new shelters build with materials from damaged homes.
* Gardeners teach and spread out work teams to plant food in every available niche. They save seed to plant more.
* Larger-scale survival is like a farm that depends on manual labor -- the more laborers, the more work gets done.
Sue