Thanks for posting in the Community, @fabrizio.iacono. I can lend a hand with an employee that lives and works in another state.
The following article provides an overview of multistate employment situations: About multistate employment payroll situations. It provides helpful insight into payroll areas, such as reciprocity agreements.
This resource is a good place to start when looking at a scenario of employees being in multiple states.
Please let me know if you should have any questions. Have a good one.