CS4 symbol prob when merging FLA's into one


I have several files for every piece of my movie. I have SCENE1.FLA, SCENE2.FLA, SCENE3.FLA, etc and want to merge them all into one file - MAIN.FLA. To avoid library symbol conflict, first I copy the content of SCENE1.FLA into MAIN.FLA, then in MAIN.FLA, I put every symbol in the library in it’s own new folder named “+SCENE1”. Then at the end of the frames of SCENE1’s content on the timeline, I make a little space (blank frames), and paste the frames of SCENE2.FLA. For some reason “resolve library conflict” window pops up and ofcourse I say "don’t replace). Now in MAIN.FLA the animation of SCENE2 has several problems: some symbols are missing and others are misplaced (like background, that is at the wrong X/Y position). So my question is: how do I get this right? How do I fix those problems and how do you usually merge the FLA’s into ONE?

Best Regards