I have some experience with this same issue . When I got certified, I used my middle name on my c card (that’s the name I use socially). Through the years so many times I seemed to be two different people, with my first name on my credit cards, passport, etc. When I most recently got my dry suit cert, the agency sent a new card. I finally gave up, and just had it sent with my first name on it. Now SSI has my dive history listed as two different people, and my card lists my number of dives as many less than actual. It only lists the dives done under my new card/name. They said they could merge the two accounts, but it is a bit of trouble, with lots of forms. So, my advice is to choose the name you want to use, not with the idea of changing it later.