Hi,
the map in this example is just a krpano viewer and therefore it supports the same features as krpano itself.
That means for 'overlays' currently only hotspots could be used, no other multires images.
But one solution could be using the tiles from a different map/source for a particular map-range in the 'customParseTilePath' action.
E.g. check there if h, v, and level are within the range of your overlay image and map the indices and files urls accordingly.
And for dynamically blending in/out a custom flag could be used and a scene reloading with the keepview flag.
Best regards,
Klaus