Private call using cisco jtapi

Q. From the following scenario :

1. User A , B and C ... etc are in conference call through cti terminal

2. User A makes call to external user say it as User D , this call should be a private call between User A and User D ,

3. Once User D ready to join conference call , all users should be merge in the same conference call which was initiated in the step 1 .

We are able to implement step 1 and step 3 , but unable to find anything in the cisco jtapi for making private call, please let us know if any idea on that ?

A. This solution can be used,
Call between A and D will be consultation call before merging into the previous call and that will be private. B & C won't be able to hear the consult call going on between A & D.