Just to expand on what @IanH said.
You can make a base plan from a project plan by holding down Shift while clicking on Manage Plans from inside the Project Plan dialog. This will show a new button that lets you save your current plan as a base plan (it will be put into the _StandardPlans folder in your My Paratext 8 Projects directory). You can then give out that plan to other people by having them copy it into their _StandardPlans folder.
In 9.1, there is also a new hidden menu option that lets you easily create updates to your plan. To get to this new menu option, you need to hold Shift while clicking on the main Paratext menu, then click on Paratext > Support and development > Base project plans. This will show a blank project plan dialog where you can load your previous plan by clicking on Manage Plans. You can then edit the plan and then save it as an update which you can then distribute.
(Sorry creating updates is a little awkward to do, but it was quickly thrown together using existing code to help only the few people that manage the base plans)
If you don’t use 9.1 to make an update, then there are some important things to consider when creating an update to a plan:
- The ID of the plan must be the same (i.e. the GUID in the <PlanId> element in the file).
- Make sure that the IDs of the stages, tasks, and checks are the same. If the IDs change, Paratext will consider them different and will not migrate existing progress data.