Difficult question?? Discontinued Parts with replace function????

Question

Hi Experts
In our company ,there is a requirement very emergent , as follow example:
In the BOM of material CDE, there is a component material A.
And for some reasons(for example: product development with new technique) ,we want to replace
material A with material B in the BOM. And because the stock of A in the warehouse is not zero,so we
want to continue use material A for a period.
And when the stock of A in the warehouse is zero 0 ,means that A has use out, we want to the SAP system automatictlly replace material A with material B in the BOM.
I konw I can use "discontinued Parts" , but with "discontinued Parts",the system only can transfer
all the dependent requirements of the discontinuation material  to the follow-up material, not replace the  discontinuation material with the follow-up material in the BOM really! 
We want with "discontinued parts", the system can replace the discontinuation material with the follow-up material in the BOM really ?
How to achieve this?? Or if there is some other functions can achieve this??
Thanks for any reply!!

Answer 1

Dear Fei,
What's your exact doubt?
If you want to stop using a component from a certain date and instead you would like to replace the
same using another followup material which has the same unit of measure,then you can do the
necessary settings in MRP4 view of the material master.
One more concept is alternative Item concept,where in some period material A will be available for some
period and in some other period B may be available and in sometimes a combination of both will be
used.
Then in that cases in the BOM an alternative item group will be created to combinae these 2
components along with their priority,usage probability and strategy.
Regards
Mangalraj.S