Can I combine Quicktime .m4v files with captions into a single file?

I have .m4v (Apple TV) files that are close-captioned that I need to combine and maintain their captions. I have tried combining the files using the Add Clip to End command in Quicktime, but the captions apparently have been removed in the combined file. Is there a way I can combine files and keep the captions so they can be shown?