More like making your big project in multiple small, manageable MLT project files and saving them into the same folder. Then you can quickly switch between them in the Files panel.
This is more or less the same as having multiple timelines or sequences.
- Make sure all your project MLT files are in the same folder.
- Make sure your current project is saved.
- Open the Files panel.
- Open the Location drop-down list.
- Choose Current Project
- Double-click on the other project file you want to switch to.