Open the Manage Databases dialog, and go to the Relationships tab.
Create new Table Occurrences for every table that you are syncing with. You should give this TO a consistent name, based on the Table name. We use "TableName.RESTfm" so the name is the same as our Layout name from the previous step. This makes it much easier to work with.
Join all of these new TOs to the RESTfmSync TO by joining the RESTfmGlobalID to the unique ( UUID ) field mention earlier.
Every relationship needs "Allow Creation..." and "Delete Related Records..." turned on.