We are trying to build a system with reusable plans - where a plan is essentially a step-by-step instructions plus timing data. So the idea is - somebody creates a good plan - like a recipe, or first 10 weeks of life of a child - and then many people should be able use it.
So master plan should remain the same, in our opinion. On the other hand, you can change positions of steps, add/remove reminders and if you are not satisfied with the plan completely, you can duplicate it and create a new one based on existing.
We are not trying to create yet another project management tool - it is more of tutorial with timeline, reminders, images, videos and reusability is the main focus for us.
I'm curious, once you publish it, why can't you go back and edit it again? (I know of almost no plans that don't get revised during the process)