Sender Pre-fill Custom Fields

I want to be able to create custom text fields (addresses of property’s) so that they can be selected as required into a Sender pre-fill text box.  Currently this is not possible under the Sender Prefill “user” as far as I can see.  I can only create them under my own name.

If this is possible I would be delighted to hear how to do this.  If not, DocuSign developers can you get this implemented asap.

Thanks

Richard