I acknowledge that packages which are linked to single-player mode are saved in C:\Users\<login>\AppData\Local\Deng Team\Doomsday Engine\runtime\configs\game.dei. No question there.
However, it's apparent that linking local packages to multiplayer mode are saved to a separate file that I cannot locate. The settings are not saved to the same game.dei; if I remove a package from the single-player configuration, it remains linked to the multiplayer game. C:\Users\<login>\AppData\Local\Deng Team\Doomsday Engine\server-runtime\configs\game.dei seemed like the obvious choice, but it shows an empty template for the games supported, but none of the 3rd-party packages are listed regardless of any config changes I make in multiplayer-mode.