Hybris Marketing 1709 - Loading Contact from external system

Hello fellow SAPians,

In the process of implementing yMKT 1709. As part of that, we are supposed to load thousands of contacts in to the yMKT system. I have ODATA services - API_MKT_CONTACT_SRV to leverage for Contacts. However, the this API service doesn't seem to support POST method for Contact Entity set. Basically, creating of a new contact seem to be not possible - but can update and add teammembers etc. I was also looking in to CUAN_IMPORT_SRV. But it seem to be specific to hybris Marketing Cloud. Not sure it can be leveraged for On-Prem too. Any directions for the best way to leverage loading of the contacts and also to have up-to-date by syncing up the source system?

Thanks

Rajan.