[Jocelyn84]

DBL, I tried it by resetting my cache, going to sprint.com/citigroup, then opening a new tab and picking add a line. Unfortunately, I think it pulls you out of the citigroup store after you log in, making what you want to do impossible.
The only thing I can think of is, starting a new line/account, then doing a transfer of liability for the new line to your current account. I did just that to get sero about 2 years ago, but I'm not 100% on how it all works now.