When you go to edit a TeamRaiser, the "Manage Stationery" step is there for you to create stationery that is specific to that TeamRaiser. So if you create a stationery here, it will only be available to be used for this specific TeamRaiser. However, as long as you do not have the box checked next to "Use Only Event Stationery" that says " Yes, allow Participants to select only Stationery selected for this TeamRaiser event", other stationery you've created outside of TeamRaiser (under Email > Stationery) will be available for participant center and coaching emails as long as it has the proper security category.