I wrote module for asterisk transit server and call centre. EGW module content main table with extra data table and any other tables with extra data tables. However i make links and describe in user interface my objects (main table and some other tables) and link this objects with other EGW objects. For example:
-did (group phone)
-user call dialog (dialog for describe answers - use site admin module)
-cdr (calls log)
asterisk module contents cdr, proxy trunk and did objects.
I don't search in source code some modules contents more one object to link with other objects.