Multiplayer TAS in singleplayer using fake players

[ScribbleTAS]

A really fun "late game" feature is the creation of fake Minecraft players.

Then when recording, you'd be able to switch to the fake player and "take over", allowing you to set the inputs. Then you can record a TAS for multiple people in singleplayer.

Recording a TAS like this should be pretty easy to implement (if you know how to create fake players), however playback is another story...
How do you accurately run the inputs through a fake player, without having control over it?

Also you would be able to make comparisons like ghosts for TASCompetitions etc...