In AX 2012 R2, InterUnit payable / receivable functionality was introduced with 'Balanced dimension' feature. 

This feature allows you to maintain multiple Legal entities (complete Trial Balance for each of the LE) within a Company in Dynamics 365 FO. 

If user posts entries across multiple dimension values (for the balanced dimension defined in the system), Due from and Due to entries are posted automatically between InterUnit receivable and InterUnit payable accounts. 

However, this functionality lacks visibility into Due To and Due from by Legal entity/Business Unit. This is major limitation in using this functionality.

Similarly, while setting up Intercompany accounts between Legal entities (Companies), you have to create separate GL accounts to have visibility into "Due to USMF", "Due from USRT" and so on. You can't get way by using just "Intercompany dimension" on your COA.