Supplier Schedule Information for Transfer Orders

Our company exports to other subsidiary companies.  We have a regular schedule of when containers leave.  However, there is no process in JDE I can see to reflect this for planning purposes.  For example, MRP uses the shop floor calendar for delivery purposes.  But, the assumption is that the inventory can be shipped any day the office is open instead of a shipment pattern or date.  In order words, if the container leaves on March 15th and the next container is not scheduled until April 15th, MRP does not move up all the potential shipments between 3/15 and 4/14 to