GroupWise doesn’t use its own API. When you proxy, GroupWise uses it’s own internal processes to provide the functionality you see. Formativ cannot expose this behaviour to third parties.
The GroupWise programming interface, broadly speaking, is divided into two main areas:
1) The Object API, which is used to access data that exists in the message store. The Object API is account-based, and is not associated with the GroupWise user interface in any way. For example, you don’t even need to see any GroupWise UI in order use the Object API. The Object API exposes the Clone and AddExistingMessage methods you have used. Formativ fully exposes this API.
2) The Token API. The Token API represents the commands that you generally execute from the client, such as created a new email message and seeing the new email message compose dialog appear. The Token API commands operate on the client in whatever state it finds it. For example, if you proxy to another account then call a token that deletes the current item (owned by the user who’s account you proxied to), as long as you have the appropriate security the item is deleted.
There is no simple way I know of to have the Account object automatically login to the account you have just proxied to. While the security exists to access other items when you proxy to another account, this security is applied at the GroupWise client level, not the API level.
It may be possible to acheive much of what you need to do using the token commands. Have a look at the GroupWise.Item… commands in the language guide. These commands essentially map back to native GroupWise tokens, and operate on whatever items are currently selected (regardless of whether you have proxied or not). Also, have a look at the ItemListCreate commands. However, to use any objects or methods under the Account object (such as clone), you need to be logged into the account you wish to access.
I hope this helps.