You need to check each adaptor and see if all the 4 blocks are fully populated especially the two circled on the diagramn, I don't think the PnP hardness for the Amp is so that needs to go to the car side
If the MDI and Bluetooth adaptors are fully populated they need to go closest to the car
Option 1: RNS510 - MDI - Amp - parrot kit - vw harness - Won't work
Option 2: RNS510 - Amp - MDI - parrot kit - vw harness - Won't work
Option 3: RNS510 - parrot - MDI - amp - vw harness - possible
Option 4 RNS510 - MDI - parrot - amp - vw harness - possible
Be aware that the more adaptors you have fitted the more of a risk of intermittent operation
If you are going to upgrade to the VW bluetooth, it will be worth modifying the MDI adaptor to install the extra wires into instead of having three adaptors fitted