Account and Subscriptions
How can I add a product to an existing subscription?
At this time, you are not able to add items to an existing subscription through the Subscriptions page. To add an item, you will need to place a new order for the product you would like and place it on subscription.
After the new subscription is created, you can update its next order date and delivery frequency to match your existing subscription. Future orders scheduled for the same date will automatically be combined when processed, provided they use the same shipping address and payment method. Your subscriptions may continue to appear separately until that order date.