I am trying to determine whether it is possible to display the "compact layout" of a record in the Chatter Feed of another object type. I know that it is possible when the two objects are related via a lookup, as it uses the CreateRecordEvent type of FeedItem when you create the child record via a publisher action. However, I am attempting to create a child object where the relationship is loosely defined (a text field that holds the ID, allowing the object to be used with any other object) via a custom Visualforce publisher action on the Account page.
To illustrate, the FeedItem below is a new contact that I created on the Account page using a publisher action. It shows up on both the Account and the Contact's Feed.
I can create a different type of FeedItem like a LinkPost to reference the URL of my loosely related record, but would like to maintain the format of a CreateRecordEvent and the compact layout that displays metadata.