In ServiceBox, you always have an "Assigned" User (top page of Work Order) and then a separate "Scheduled" User(s) (third last page/calendar icon button, on the upper right of the Work Order) for any one Work Order.
The Assigned User is not necessarily an individual who actual does any physical labour on the Work Order to complete the "job". They may be a Project Manager or Foreman for the "job". It is the person who is responsible to see that the job is Closed and that the company can then Invoice the Work Order, and create revenue. The Scheduled User is the person who will do the physical work on the Work Order/job. That said, in most smaller companies ServiceBox has as clients, the Assigned User may very well be the Scheduled User on the Work Order, to work on and complete the "job".
If you create a Work Order in ServiceBox and want to put it on your Scheduler, but you do not know which User will be able to actually Scheduled on the Work Order at the time of creation, we have a way of doing this. What has worked very well for our customers is to "Assign" the Work Order to someone in the company who NEVER goes out to do physical work on a "job" - like an Office Manager, or receptionist. This way, when you physically see their colour on the Schedule when you are looking ahead to book in jobs, you can tell that a Work Order does not have a correct field tech User scheduled to this job, as the colour is incorrect. The job is still located on the Scheduler where you want it, but User is there that does not physically work on jobs.