Just clicked “Change Plan” to upgrade to a higher tier, but I can't select the add-on during the upgrade; this is only possible when purchasing for the first time. Can I just purchase a Tier 1 plan with the add-on and then assign the add-on to my existing account? This is still a new campaign, so you may want to discuss this with Appsumo—when the sale ends, many people will surely decide to upgrade, and then it should work... For now, I can wait and upgrade later