I've created a ContentType in my data migration that welds several ContentParts together.
On the Orchard Site Content Admin I can add a field to the ContentType (but not a ContentPart), and in the data migration it only seems possible to add a field to a ContentPart (and not a ContentType).
I would like to add the field to the ContentType in the migration, so I can control it's placement using placement.info.
Perhaps that's not important, and there is another way to achieve adding a field in the migration and then being able to control where it is placed using placement.info and how it looks using a template.