Hello
Since you have an old material and a new material, I suggest you to use the discontinuation process.
On the master tab MRP4, you can define the new material as the follow-up of the new material.
Requirements for the new material will be re-directed to the new material during the MRP run.
See the following note for more details and some restrictions of this functionality:
43636 - Discontinued parts
BR
Caetano