It's a good question. We normally just say WPS qualified for all P-1/S-1 materials, as specified in ASME Section IX, QW-422.
You will have to do some educating, but people will come around.
Charles.
I normally put the material specification as well as the P No. on the PQR, and then put the P No. as a minimum on the WPS (and group No. if impact testing is required, but since you are using WCC, it shouldn't be). I also list material specifications on the WPS when it seems appropriate, but I don't think it is required.
Make sure what material you have though. If you have ASTM A216 Gr. WCC as opposed to ASME SA216 Gr. WCC, then the material is S No. 1, group 2, not P No. 1. Then if you qualify on an S No. material, you can not use it later for P No. material, but you can use a procedure qualified on P No. material to weld S No. material.