I’m trying to sketch this out, but it looks to me like it can’t be done with a P2 setup – you would need to put PK back in the PK slot so that Y can be used to replace one of the bad channels. GR can be used for the other.
Normally you would just move the LC/3 and LM/5 to OR and GR but you say OR is also bad. The only other option I see is to give up the LLK/GO channel for one of the channels that needs remapping. LLK/GO is not used in these PiezoDN curves, so unless you need GO for something else (glossy prints on paper) that might be an option. Is there a reason you are running P2? Bad K switch?
If I’m looking at this correctly, rather than using a P2 curve, you would have to go back to a regular setup from which you remap LC to Y (shade 3) and LM to GR (shade 5). Both MK and PK would be in the normal positions rather than PK being in Y. The remapping would look like this:
PS - You will need to use PPEv2 for remapping. Both tool versions can be used for PiezoDN, but v1 (Smoother, etc) is for PiezoDN only, while PPEv2 is for all Piezography printing including PiezoDN. At least that is my understanding.
PPS - As usual, I could be completely wrong about all of this.