Add post to existing topic with Zapier

I’ve been playing with Zapier a bit and am able to use it to add a new topic to a category in my Discourse site. So far it’s performing as expected, except for one thing.

There doesn’t seem to be a way to both create a new topic and add replies to an existing topic from Zapier. If I send a 2nd post with the same topic as a prior one then I get an error instead of it being added to the existing topic as a new reply.

Has anybody found a way to do that?