Hello
Again, if you don't need to plan your materials until the receipt of a stock transfer, I don't see any relevance of using PIRs.
You should think about simplifying this scenario and getting rid of PIRs, as they will only add an unnecessary complexity.
Otherwise, if you really want to work with PIRs, you should think about a custom solution using BAdI MD_CHANGE_MRP_DATA to make them not relevant to MRP.
Regards
Caetano