Hello RalphL,
You do not need to update all the software. You will need to install the only required software for the vehicle you are working on. It will not effect on the vehicles you are working on. You will need update for Ford for latest update.
However it is recommended to updates other vehicles in case you need to work on other vehicles. You can choose to do those updates with another back up sd card if want to.
If you have any questions, please let me know.