There could be option for gang leaders (optional, so you can choose not to have this feature) to execute robbery right after needed number of people joined.

For FK where you need 18 people, after 18th person joined, it would execute robbery and others won't be able to join. They will be able to join for next robbery.



I think it would be of help to many desperate players who complain about too many people joining robberies, so you rob very low amounts of money.