There are many ways here are a few. I suggest going with the first method.
- Select all items on the timeline in the minute long composition , copy , then go to your your 6 second comp, position your insertion bar to the end and paste the keyframes, you may need to extend the length of your composition in your settings
- render out each composition to a format such as .mp4, and then import each into a new composition
- precompose each of your compositions, and copy and paste them into a new composition. Either method will work, you can think of precomposing as grouping if you are new to after effects
render out each composition to a format such as .mp4, and then import each into a new composition
Disagree with this part. You do not want to render to a compressed format like MP4 and then continue working on it. Render to a proper mezzanine codec (intermediate codec, production codec, whatever you want to call it). Something like QuickTime with the PNG codec, Cineform, DNxHD, etc.
Here is how I would do it:
- Save the project with the six-second comp as "Merged Project"
- Import the project with the one-minute comp into "Merged Comp." It will show up in a folder.
- Reveal the contents of said folder and find the one-minute comp
- Drag this entire one-minute comp into the timeline of your six-second comp. If needed, set the duration of this comp to be 1min and 6 sec. Select the minute long comp in the time line, go to the 6-second point and hit "["