My suggestion would be to ask your referring SSI instructor to help you with this. He or she should be happy to help to make sure that the SSI process is followed.
PADI shops can take your referral, but PADI uses a different process. SSI uses what is called a universal referral system. In this system, you can get certified by a different agency, but the credit for the certification goes to SSI and the instructor who originally referred you. Thus, if you found a NAUI shop on Antigua, they could do the certification dives for you and you would still be SSI certified, and your home SSI instructor would get credit for that certification.
PADI does not
officially support that process, though. They believe there is a problem with an instructor and agency certifying a diver without seeing that diver actually perform in the open water. In the PADI system, the PADI shop can accept the referral, but the certification will be PADI because it is a PADI instructor who supervised and observed the certification dives.
PADI does, however, allow individual shops and instructors to use the universal system if they choose. It is therefore possible that a PADI shop in Antigua will be willing to do the OW dives with you and still have you become an SSI-certified diver under the universal system. You will need to check ahead, though, to be sure that is what will happen.
I think you can see why your SSI instructor should be motivated to help you with this.
---------- Post added December 24th, 2014 at 11:05 AM ----------
Ultra Marine says it offers SSI instruction:
Ultramarine Club Colonna (North)
Sunsail's Club Colonna Resort
Hodges Bay
Antigua
West Indies
Tel: +1 (268) 463 3483
Fax: +1 (268) 560 5062
E-mail:
andrewm@ultramarinecaribbean.com
Ultramarine St. James Club (South East)
Mamora Bay