I feel like I'm missing something really obvious here. Are there no suite functions to reorder layers?
I've tried getting the layer's group art and using AIArtSuite->ReorderArt with eg. kPlaceAboveAll, but this just moves my layer inside the top layer, rather than above it.
Seems to work by using ReorderArt kPlaceAbove and the topmost layer group art as the prep.
I was just about to chime in on that score. I just looked at how we do it, and yeah, that's exactly how we do it too. I believe that's the only way.