Hi @darren_winch1, welcome to the Community! I’m not sure how the Party Mix 2 is MIDI mapped by default. However, if the Instant FX are already MIDI mapped to one of the pad modes, you just need to edit the Instant FX for one of the pads and change it to Flanger 4.
Hello! It’s been a week since my last reply. I’m going to consider this topic completed for now so I can focus on others. However, please feel free to respond and we can definitely revisit this. Thanks!