Mark scenes as 'in modification' or as 'modified' or make a scene unselectable?

Hi,

In order to avoid merge conflicts and loss of work with git, my team need to find a way to mark scenes in real-time as "in modification" or as "done". If it's not possible, we are also be interested in making a scene unselectable.

Can you recommend us a plugin? If not, how can we mark scenes with custom marks or make a scene unselectable in the project window by scripting?