Even if you manage somehow to add the PIC you want in the list, compiler will not be aware of this new chip. Compiler needs more files related to that specific chip and also have an assembler that will support it.

So, the latest assembler supported is in the 5.35 MPLABX IDE.

I am afraid that there will be no answer from Mecanique and no update now on for any new PIC. Either you have to stay with what is available with PBP or look for other compiler, preferably in C.

Unfortunately PBP is dead and we have not accepted the fact yet... Well some did and moved on to C compilers or Positron Basic compiler.

Ioannis