Don't understand your question.
G28 is required only to establish the fact that you have an attorney, and to authorize the attorney to act on your behalf.
If you change lawyers, you will still file G28 with any new application.
I am not aware of the procedure of substituting your old G28 with a new one... talk to your new lawyer, or someone here in this forum who has done it before may be able to help.
For anything that you file by yourself, a G28 is obviously unncecessary.
