Khan Academy API | How can we have a user send a message into a thread?

I have an idea for a contest I am helping put together, that rather than have a user find the thread below, they can input their text directly from the website, and send it into the thread into the right format, which will stop them from messing up the format (reading the replies using .includes and sorting them into different categories).

Is there an API function which I could use where when the user presses the button it will send their message into the right thread? Is this against the guidelines?

I will have a warning asking them to confirm, if that is an issue.