Passing more than previous message to JSON API interaction

Hi,

I'd like to send data to an external API using a JSON API interaction. However I can't find any instruction to pass extracted data from several previous interactions. The only thing I can currently pass is the response to the previous interaction.

Is it possible to pass several messages using a JSON API? For example, is it possible to add extra fields into the JSON object that is sent? Or can I include these data into the url?

Thanks for your help!