iirc, my stardock central login worked on both; either that, or I put my keys into Impulse to associate them with my Impulse account.  I do recall that I didn't need any outside assistance - at that time, which *was* a transitory period, so that may have changed.

If neither of those work, I would e-mail them at their direct support e-mail address (these forums are more for other-user support).  They have always gotten back to me within a few days when I had issues such as a changed e-mail address.  Seems like I had an issue similar to this once where I had something associated under a different e-mail address and I needed it moved, and they did that for me, too.