MRP considering total lead time

MRP considering total lead time for sugg. due date and not the dock date(pre-processing& processing) for PO due date the MRP plan is referring to SO schedule ship date and try to match the SO ship date -- and recommanding the PO to be re-schedule to a date similar to SO Ship date. This is wrong. We have other activity in our warehouse after we have the item in inventory. MRP should take only Pre-processing and Processing lead time and plan the order. Expectation of the MRP recommandation (which is not happening now) For example Item have lead time lilke Pre-processing time: 2 (processing PO) Processing time: 3 ( Maufacture at supplier end) Post processing time: 5( inspection in our warehouse and documentation) We need to use MRP to plan for Supplier's promise ( ie) Pre-processing and Processing lead time excluding post processing time Let's say today's date as 9-Sep-2012 SO booked to be scheduled to be shiped to customer by 19-sep-2012( 10 days of lead time to make the item ready for customer shipment) while MRP recommand , the expectation we have is Sugg due date should be 14th Sep (2+3) --> Pre-processing and Processing lead time total..this can be handled by manually copying the sugg dock date in the implement date before releasing planned order and next time.. MRP recommands...,it should not ask to re-schedule the PO which is having the promise date as 14th Sep and also it should not plan for the SO who ship date is 19th Sep ... as we have satisifed this demand with this PO.