I contacted Ryanair help box:
All passengers (including infants/children) must carry a valid passport, so it is important that you check the expiry date before you book your flight. Your passport needs to be valid for the period of intended stay or you may be refused entry.
If you need to make changes to your Travel Documents or any companions under your MyRyanair account, please login through ourwebsite and access your ‘Dashboard.’ Click ‘Passengers’ on the left hand menu and select "Edit" or "Add document" - make sure you click Save.
should be fine