The "save mission" feature will leave behind empty groups

[jboecker]

If all units of a group are destroyed, the group will stay in the mission. This will look weird when displayed in the DCS Mission Editor, but does not seem to cause any problems.

It may even be a good idea to leave it as it is, so a mission script can still get the group with Group.getByName -- I do not know enough about the DCS scripting environment to decide this.