Merge pull request #5581 from segmentio/spencerattick-patch-5

Multiple External IDs

Author: rchinn1

src/connections/destinations/catalog/actions-facebook-conversions-api/index.md

@@ -211,3 +211,7 @@ After you start sending events, you should start seeing them in twenty minutes.
 2. Click on the corresponding pixel.
 3. In the Overview tab, look for events where the “Connection Method” is Server.
 
+### Send multiple External IDs
+
+[Facebook](https://developers.facebook.com/docs/marketing-api/conversions-api/parameters/external-id/){:target="_blank"} allows you to send one External ID per payload as a string, or multiple per payload in an array of External ID strings. Send an array of External IDs through Segment by mapping an array to the `externalId` field when setting up your Actions mappings.
+