When you want to make a unit, or group playable you have to edit each individual unit.

Make multiple units and or groups playable at once via menu

What I'd like to see is a feature implemented in the editor that effects both Sp and MP where you can highlight the selected units you want and make them all playable at once.
Heres how this would work, normally you need to draw a box or click on a unit to highlight them in order to edit them.
Doing the same with the new feature would bring up a small menu instead of the edit unit box, although you should still have this feature where you can edit an individual unit, in this menu you would have a list of various options, one option here is to "make playable" so when you click on this option then that will make all the units highlighted all playable.
the other option to this is to add the list to the already existing edit unit window that pops up when you edit a unit, but then after hihglighting several units, or a group to several groups then the window would change to adjust for the new added numbers of units, putting them into a list that can be also broken down to then edit an individual unit if needed.

Ranks

Other options in that menu would allow you to change the rank of all units, like it could say ranks, and then the editor would list all units highlighted then you could adjust the ranks of each unit individually without having to edit a unit one at a time just to change their rank.

Commands and Codes

Commands and codes can be done the same way to a degree where you can have in the edit unit a list of all the things you want to do based on what i described above, but now have the option to add codes to multiple units as well to the init line of units.

imagine having to add a code to lets say 5 Ai squads, and you need to add a code to the squad leader for each squad, with the idea, you can have the option where highest rank is listed first, you could have a check box where all units are listed and then their ranks, from there maybe check all the boxes of all the squad leaders and then somewhere you would get an option to add text/code to an open box like you normally would when you edit a single unit.

Sp and MP

Overall i think having such feature making it simple of course and contained, you would really cut down on the amount of time it takes to edit a mission.

For single player highlighting multiple units and making them all playable enables you to switch to those units now playable when you die, allowing to to choose those units, for mp it would allow for slots to be chose and playable, which in mp already does but for the sake of time if you have to add lets say 20 units, and add codes, to each unit, and then make them all playable, it would take you almost a minute per unit to do so, so ideally if you had a window or a dialogue that would simplify this method then the amount of time needed to edit would be seriously reduced.