Hi,
Simply having the PIC showing up in the drop-down list (which is Mecanique and MCSP's job) isn't enough, you need the .inc files for the new chips too which, if you don't write them up yourself, will have to come from MELABS with an upgrade of PBP. In other words, first there has to be support for the particular added to PBP then Mecanique may add it to the drop-down list.

I seem to remember there was a way to add entries to list "manually" but I can't remember where I've seen it. But again, before there's support for the chip in PBB it won't matter much.