What is the post body to create a custom object via the API?

[Erik_Heldebro2]

Looking back at your post, it seems like you are trying to update a custom object that doesn't exist. The data structure needs to be defined in order to sync a custom object to a lead.

The relationship is one-to-many/many-to-many meaning you can push multiple entries to a custom object on a lead and they will exist in the Lead's Detail under the Custom Object's tab which can in turn be used to filter off a value of a custom object/trigger off the custom object being added to the lead.

[Kenny_Elkington]

The API you're referring to is only for creating and updating custom object records, we do not currently offer an API for managing custom object ​types​.

[Mark_Price]

ahh, you are right.   There isn't a way to create the custom object type. Thanks for the help as I'm figuring out the same problem as Danielle. Any idea if that's on the roadmap (?)