Merge Request Webhooks Not Triggered Appropriately

I need to send a Slack message any time a Merge Request is:
Commented On

For compliance purposes, this is being set up via Zapier Webhooks as incoming hooks. In GitLab, I set up 3 webhooks using 3 different URL’s, with specified messages for each type of event. In Zapier, I tested each payload accordingly, and everything worked as expected when testing these webhooks individually. Meaning, I was able to see 3 separate messages being sent to Slack.

However, I’m confused now about how to differentiate between the triggers, since the only option I see for a trigger is “Merge Request Event”. Specifically, now when I create a Merge Request, all 3 messages get sent to Slack at once (created, commented, and merged, even though the only actual event that occurred is created). How do I actually different between the different events, so that when I create a MR a specific body of text is sent in Slack, and when I comment on a MR a different message is sent, if this all falls under the umbrella of “Merge Request Events”?