Hi Javier,
You can also try to create a temporary table with an xds() method which returns a list with "my" transfer orders. Then you can apply x++ logic to define which transfer orders would be visible. Note that it might cause performance problems with large number of transfer orders that needs to be visible. If you filter on e.g. active and only certain warehouses, it might be OK, but you have to test it. An example is the table MyRoles. In the security policy you can then use this table as basic input for transfer orders. Possibly you have to create a separate security policy for the transfer orders.