Making capacitors stackable

[ThinkSome]

I have decided that I want to remove what I perceive as unreasonable limitations in game, such as the inability to install more than one capacitor. How to achieve this?

I have noticed that SPEC capacitors are already stackable. They are (like regular capacitors) marked as Upgrade_Additive. I assume that this is *supposed* to add up the stats of all SPEC capacitors together. So what remains is to give the player the ability to install multiple.

This limitation seems to be implemented by ;upgrades/Capacitors:1; line in units/units.csv (and also in ship csvs in save directory). When I remove that, I can install more capacitors. However

1) I can only install larger capacitors. Installing cap I, cap II and cap X will allow to install XI to XV, but not III to IX.
2) The resulting capacitance on the info/ship stats is the maximum of all installed capacitances. What does Upgrade_Additive even do?