If you want to load secondary swf file, you must have to create a SWF object and place you swf object onto the Window object. Please follow the steps below:
1. Create a Window Object say window1.
2. Create a SWF object say swf1.
3. Create a basic object say bas1.
4. Create a script with the following actions:
Open Window
Load SWF > External Ref.
5. Assign Script > Run action to bas1 object.
Hope it helps, If you have another doubts please get back to us.