No, day ticket upgrades are only available when purchasing a Merlin Annual Pass, not Memberships. You will need to purchase your Annual Pass on the day of the visit to an attraction before going home. You will then be given a voucher to create your pass online.
Please note, upgrades can only be purchased on the day. You are not able to purchase an upgrade after your visit has taken place.
Please keep these safe as we are unable to replace any lost or damaged vouchers.