How can my students share iMovie project files?

My students are recording and editing a video for a project. The students all have individual iPads to use but it is a group project and I want students to be able to send not just video files to each other but the actual project files so that each person is able to edit them.

Students within a group may be in different class periods and students may be absent so it is very important that the movie is accessible to everyone in the group from each of their devices.

Some ideas I had were exporting the project files from iMovie to either dropbox or Google Drive and having them share it with everyone else in the group, allowing them to import it into their own iMovie, but I don't know if that is possible.