...
If you cannot assign a manager or reportee when creating a user using a POST request, because the user ID is not available until after the user has been created, use a separate API call to add managers to a userassign managers/reportees.
Custom Profile Fields
Remember that whilst the Settings options will be standard for all customers, the fields listed below the user’s Profile will be specific and unique for each customer. To see what custom profile options are configured for a Fuse instance, refer to the API documentation on that instance:https://<instance_name>.fuseuniversal.com/site-admin/api_documentations
...