In Dynamics NAV, if you are using the warehouse functionality like warehouse receipt and warehouse shipment then you have an option to define the location wise user access but what if you are not using warehouse functionality and just doing inventory transaction.
One of my client had a same scenario, they have multiple branches and keeping stock over there. now the problem was any branch employee can post the inventory in other branch location if the user has the inventory posting rights. Their requirement to stop the user to post the inventory in other location and restrict them only to their assigned location.
Below is the solution we implemented and it worked...!!!
Create New table Called "Location Employee" with User ID and Location Code field so here you can assign the User ID against the location code. it could be single or multiple.
Once this defined, you need to write small code under codeunit 21 - Item Jnl.-Check Line under Runcheck function to find the relation of the user id and location based on the item journal line. if it is found then it is allowed or system will give error message. it is simple ..
I hope this will help you if you have same problem.