They should try to help the smaller group. Anything other than that would be contrary to Panhellenic spirit. The smaller group also needs to do some work on their own as far as COB and thinking outside the box in terms of pledging something other than the tradtional freshman rushee. They also need to emphasize their age/tradition, and due to years of alumnae, connections connections CONNECTIONS!
Firehouse, boys just don't understand this stuff, so don't try. You will be much better off.