diff --git a/classes/class-pmpromc-mailchimp-api.php b/classes/class-pmpromc-mailchimp-api.php
index 86537db..38e760d 100644
--- a/classes/class-pmpromc-mailchimp-api.php
+++ b/classes/class-pmpromc-mailchimp-api.php
@@ -171,6 +171,17 @@ public function update_audience_members( $audience = '', $updates = [] ) {
 			'members' => $updates,
 			'update_existing' => true,
 		);
+		/**
+		 * Filter the body parameter sent to the "update audience members" endpoint.
+		 *
+		 * @since TBD
+		 *
+		 * @param object $data The data to send to the Mailchimp API.
+		 * @param string $audience The audience ID being updated.
+		 *
+		 * @return object The data to send to the Mailchimp API.
+		 */
+		$data = apply_filters( 'pmpromc_update_audience_members_data', $data, $audience );
 		$url = self::$api_url . "/lists/{$audience}";
 		$args = array(
 			'method' => 'POST', // Allows us update a user ID