Map Orphan Accounts by Web Service

Hello,

We have a similar requirement on mapping accounts to users as per below link. Eg: AD account have to look for employee ID and an extension attribute for the user mapping. 

Many-to-many Account/User resolution 

So, in this case want to try the new feature of Map Orphan Accounts by Web Service. We are able to create change request successfully. However, the request is going through the fulfilment phase and failing with the AFX message 

AddUserToAccount capability is not supported on end point ******

Is the webservice Create Change Request with Map operation - does the mapping in

                --     the target application or

                --    map the users to account in RSA VIA 

I dont find any capability of AddUserToAccount in AFX.

Sean MillerBoris Lekumovich please suggest.

Thanks