I know we are going to have 2 people building at the same time BUT can you give an option to make 2 towns so, one is yours and other players theirs.
And when in Multiplayer you should add characters so you can move around and do stuff and you would be able to see the other player as another character. So basically.
If playing Co-op, every player has their own design or workshop created character, when you play, every player moves with the character and moves around like an architect man.
Hope i gave a good idea for you Developers. Keep Up The Good Work!