This is just a thought and in no way any kind of well-thought out solution. In order to control the Flash file from an external resource, you will still need to have detailed knowledge of the processing code that is written inside it. This would be necessary so that you can execute commands/functions within the Flash file. The only way I can see doing that without rewriting the Flash file would be to have your own Flash file that you dynamically load this 3rd party Flash file into and then target the function code in the loaded file as a child object. There could be all sorts of security issues involved since multiple servers could be involved.