I work on backtesting-desktop environment. In the process of exploring LEAN, there were a number of times when I had to wipe out and reinstall LEAN completely. 

Every time I do this, I have to edit Launcher/config.json.  I could have made a backup and replace the one comes with LEAN download. But the problem is that it seems config.json itself is also evolving, so a simple replacment using an old backup is risky. Not to mention that editing config.json itself can cause problem if you are not careful enough.

So my questions is: is it possible a user can write those key:value pairs to a separate file and when LEAN start up, it use layer this separate file on the top of Launcher/config.json, replacing any key:value pairs in Launcher/config.json if the same key is found in the user created file.

That way, not only we can migrate our setting easier ( of course there's still a risk of key:value pairs change over different version), it may also reduce the chance of corrupting the other settings in config.json during editing and create additional support workload for QuantConnect team.