Hi Carl
There is no standard functionality to mass update a production or process order component/requirement. You must enter the production order manually and re-read the master data.
An alternative is to use the discontinuation process, adding a follow-up material on tab MRP4 of the material master. This way, the requirement will be re-directed automatically to the follow-up material by the ATP check, after consuming all the stock of the discontinued material.
BR
Caetano