As of this date, there is still no way to switch between AMS and external spool during a print, you are stuck with either using one or another .
This seems a very easy to implement feature through a firmware update as the hardware isn’t a limiting factor .
It’s probably one of the most wanted and useful features that are currently lacking and would open up a lot of possibilites such as printing filaments that are not compatible with AMS (TPU / certain abrasives etc) while retaining multicolor functionality .
The implementation can for example be done through gcode such as M600 in combination with a specific option that in addition interacts with the AMS board to disable it until another filament switch for enabling AMS is triggered, so basically a toggle to enable / disable AMS when M600 is called .