Hello
As far as I know, this is not possible, however, you can make PIRs not relevant to LTP or MRP using BAdI MD_CHANGE_MRP_DATA. See an example using this BAdI to make an element not relevant to MRP on the blog Making an element not relevant to MRP or MD04 using BAdI MD_CHANGE_MRP_DATA
I have never tested, but it may be possible to influence the period of adjustment using BAdI MD_MRP_PARAMETERS.
BR
Caetano
