How do I add more cameras to an existing annual protect plan?

I purchased a doorcam earlier in the year and opted for a yearly plan (6 months remaining).....as I was very pleased with the product I purchased a further 4 security cameras. I am now considering opting for a yearly protect plan to cover the newly purchased 4 cameras and the doorcam (all in one plan). How can I arrange this considering I already have a plan in place??? What are my options?