During migration, the Niagara Role is created for each AX User in the station. If the AX station was being accessed by OBIX clients, you can probably pick the User that clients were using, and simply select the Role with that name as a starting point for N4 oBIX client access.

Consider using a separate User for each oBIX client (or client type) that accesses the station's oBIX server. This is another way to increase the security of your installation by encapsulating access and giving each user the minimum access necessary to accomplish the needed function.