Currently if a customer has paid for an upfront subscription plan (such as 12 months upfront) and logs in to order an add-on, it attaches it to the subscription renewal instead of the next shipment and does not charge them. Manual intervention is required to remove the add-on and either charge manually and add a tag or create an ad-hoc order. Customers should be able to select an add-on mid way through their plan and it to be charged and added to their next shipment.