Hi Alexandr
If the process order is not considered by the strategy, system will always create new planned orders, as soon as you convert the existing planned orders to process orders. That would lead to excess stock and, in my opinion, it does not make sense.
This functionality does not exist on the standard system, however, you make the existing process orders not relevant to MRP, using BAdI MD_CHANGE_MRP_DATA. See the blog Making an element not relevant to MRP or MD04 using BAdI MD_CHANGE_MRP_DATA with an example of how to use this BAdI.
BR
Caetano
