What is a solid example (who, what, where, when, why, how,what happened?) for how regional alliances expanding their roles to include...

Regional organizations in Africa and South America have often attempted peace keeping or mediating roles, as in the Agentine-Chile conflicts, the Falklands War, and numerous African conflicts (Congo, Nigeria, Rwanda).  Some newer regional alliance groups have arisen which are mainly concerned with more limited agendas, such as economic cooperation or organized diplomatic resistance to particular other nations or groups.  These may actually in the long run have more positive effects on restraining wars than more conventional peacekeeping missions, which have usually been launched only after situations are already disastrous.  The South American Alliance, for instance, is largely a group of nations opposing US economic and political objectives on that continent.  Ethno-regional alliance groups both between and within African countries have a possibility of diplomatically working out problems which have traditionally been addressed by warfare.  The World Trade Organisation wants Pakistan and India to grant one another Most Favored Nation status, hoping economic cooperation will lead to better relations.  Will these ideas and organisations work?  We'll see.

The Organisation of African Unity, today the African Union, has not only been used for political and economic association but for peacekeeping initiatives and military peacekeeping missions many times since it's founding in 1963.  The Organisation of American States is the oldest regional cooperative group in the world.  Links to these group's websites are below, and may give you a better understanding of the potential of such organisations, as well as specific examples of their work in the past.