Thank you for getting back so quickly. This worked, but for a larger subplot (~10 heatmaps of size 3x7) it added about 5 seconds (increased from ~1 second with the update_layout to 6 seconds with the add_annotation) to the run time prior to rendering the figure. Any suggestions on how to speed it up? Not sure if it would work to only add the missing annotations rather than all of them, though this is not the cleanest approach. Thank you!