Unfortunately, we do not have a way to facilitate adding an additional rest week without “breaking” the Plan Builder training plan. What this means is that once you push the week, you will no longer have the ability to edit your training plan.
Additionally, pushing a week of training will push all of your training by a week, which means your peak will no longer line up with your planned event. We are working on simplifying this process in an effort to improve usability, however, we do not have a good workaround for the time being.
For creating master’s plans with additional weeks of rest, your best option will be to manually add and edit each plan according to your timeline.
I’m sorry I don’t have a better solution for you at the moment, but rest assured, this is something we are working hard to improve.