Could I assign tours to multi-users?

You can assign specific offers to your guides by adding the guides as multi-users to your user account. You can find this feature under "Settings > Multi-User". 

First select the users to whom you want to assign specific tours. Click on the pencil to edit the users. 

Under "Grant this user access to" > "User actions" 
make a check for  "Calendar" > "only assigned availabilities". 

Save the newly created multi-users and go to the menu item “Calendar”in the account.   

Now select the desired offer by clicking on the tile. A white window will open in which you can select the multi-users previously created under "Assignee".

After the assignment, your guides (multi-users) now have access to the offer in the calendar that you have assigned to it.