How do i embed an swf file into my flash file?

Hi i’m a total newbie to the flash game here. And i’ve stumbled on a problem i cannot solve. I have this swf file, i don’t have the .fla file for it. I need it to be able to play in my current .fla file when called upon. I also really need it to be embedded. Don’t ask me why, but the client wants only one swf file, and if i load the swf in as an external file the program they use, will not be able to display this loaded swf file. My flash file works perfectly when i load it in as external and put it into a movieclip, but that’s just not what my client wants.
So i was thinking of embedding it, i don’t know if i’m thinking of this in the wrong way, and maybe you all have some suggestions for me. I don’t know how to embed it. i’m using flash cs3 and ActionScript 3. I tried importing it straight to my library and to my stage, but i end up with just a couple of graphic images that don’t work at all. I’ve tried everything i know of, read all threats i could find about it, but it seems embedding is impossible or just not done. what could i do to fix this?
I’m sorry my english is not perfect, i hope i’ve made myself clear.
I also posted this under ActionScript 3 because i wasn’t sure exactly were it belonged.