[andrewgrossi]

I found this resource very helpful when building a solution for handling multiple sub-tasks in a todo application (started with adjacency and ended with closure based on recommendations). I'm assuming this issue is limiting some of the existing software to prevent 1:n functionality. I also discovered postgres has built functionality to support tree structure so might want to investigate if you are exploring options https://www.postgresql.org/docs/9.2/static/ltree.html.