What I mean is actually create a manager proxy.
Instead of all the clients connecting to the Asterisk manager interface directly, they connect to a manager proxy program. Now you can keep the connections to the actual Asterisk manager to a minimum, possibly just one.
So your dialing program would send the request to the manager proxy which then forwards it Asterisk. The reverse for status messages, Asterisk sends it to the proxy program which can in turn send it to any connected clients.
If you look at status panel programs for Asterisk you will find this is how anything that scales for many users does things.
Here are a few links to some manager proxy's here though I do not know if any are current. Manager syntax has changed for current Asterisk releases so a dated proxy may be a problem.
http://www.voip-info.org/wiki/view/Asterisk+Manager+ProxyIt sounds like you have got software talking to the manager interface now, so making your own proxy is likely not that big of a step.