Question about multiplayer cheat enabling

[Mood1ndigo]

I was wondering whether it's possible to spawn NPCs (not bots) and activate other cheats on a multiplayer map. For instance, if my friend and I started a LAN game, is there any mod that would enable us to spawn NPCs? I know it's possible to perform certain cheats on these maps, but spawning single-player NPCs seems impossible - you can only spawn bots with boring AI scripts.

Also, is there any way to switch to a single-player map in multiplayer, or make single-player maps compatible with multiplayer? I'm only asking because I think the single-player cheats were one of the greatest aspects of this game, and to experience it with a friend would be awesome. Let me know if there's any mod that accomplishes what I've asked for.