Creating a single shared 'manager' for your business objects allows you to centralize and standardize all you instance list activities to avoid repeating code in your filters or command handlers.
Using a shared manager you can:
For more information, see:
Avoid duplicated instance list code by using a 'Controller'
Manipulate Instance Lists from RAMP Scripts
Delegate Common Tasks to your own Instance List Controller
Low Level Direct Access to the Visualization Trees.