Note this diagram does not actually show power connections to the PIC.
This looks unnecessarily complex, and it appears the PIC can choose it's own power for some reason. If you want to power a PIC from either of 2 sources, why not simply throw out this entire circuit except for D3/D4 with the anode of D3 connected to WAY1 and the anode of D4 to WAY4? (Common Cathode to VDD).