OP, yes that is what I did. I didn't want my AU's (GF) card reporting to her credit report and I asked Chase (SM) myself and they said you can just add a nick name and her last name. I.E. Jane Lynn Smith, I added an AU as L Smith. They said there is a chance it won't show up on her credit report. Also, we have different addresses so it helps (at least at the time of adding AU, we have the same address currently). End result was it never hit her credit report!

Now keep in mind there will be some picky clerks that will deny that credit card because it won't match the I.D. exactly and she's okay with that. However, that has never happened in the 2 years she's had that card and she uses it daily.

Now using a totally different name I am assuming that is okay for online purchases, however, I think it's technically illegal at a store/clerk/restaurant because it won't match an I.D. Personally I would just stick with the Middle name initial and last name.