Now achieved player distance to control parameter values through a Unity mixer snapshot transition. Thanks to Bjorn Jacobson who provided the necessary scripting information and techniques for dynamic audio within Unity. Also some useful prefabs to save time. By using the transition technique, the patch can now successfully transition between parameter values. This is still early stages and very rough but essentially uses the snapshots from Unity mixer, so the patch is running and routed to different groups.
Next steps: to expose more parameters. Explore triggering techniques. Look at consolidating script into one to further optimisation.