This quest functions on the "anything goes" principle. The people who you are able to control will be defined within the story for the moments you can control them, and currently the only controllable character is "Charles".
You basically just gotta give a command, like "[X] Pick up apple cider" to have it be considered. People can echo the commands given to give that command more weight, so if five people voted for apple cider and three people voted for orange cider, the apple cider would win in that choice outcome.
Any command you give can be used at any time, even retroactive commands, so think a little before you give a command. Beyond that, the mechanics and range of what is possible is informed through the story and the prompts therein.
I hope you will have fun with this endeavor.