This is a workaround to a workaround but I apply strict naming conventions for my processes and sub processes
BO-action00-subprocess action
For example
Contract_Create00
Contract_Create01_FindBuyer
Contract_Create02_FindSeller
It's not brilliant but it helps with being certain as to what process can be used as an operation button (the 00 ones). And it keeps all related steps together by BO and then by activity.
It would be really cool to be more graphical like Mendix and OutSystems, but they are 10 to 60 time the price of AIM.