How to update keys in the metadata json file for already minted individual tokens?

Hi all, I am trying to update the metadata of 17 individual tokens deployed using Manifold. Specifically, I a trying to add a key-value pair at the same level as the “image_url” key and “name” key. As far as I can see from the Manifold Studio interface, I can generally change the values of keys like “description”, but I cannot add any keys. The one exception being keys labeled as “Properties” in the UI, which would fall under the “attributes” key rather than at the same level as the “attributes” and “image_url” and “name” keys. How can I add a new key at the same level as the “attributes” and “image_url” and “name” keys? Note that I do not have a burn and redeem page/mechanism afaik. My token contract address is https://etherscan.io/address/0xafa6cf05c662d836b0d6d8124d7af839239e736e . (I searched similar Forum posts, but none seemed to provide an answer to my particular question.)

You can add keys at the same level by selecting hidden attributes.