I just read more old posts than I wanted to about X1, so give up.
 
Situation: Did a reload from ground zero and while fighting driver issues, I went with basic program installations of X1->X3. Going back I loaded X1 components (not the program), but was forced to enter the original X1 S/N. X1 still comes up as "Expanded" (D), and now have the dilemma of the S/N cannot be changed, and the S/N and Reg Code mismatch. As I already installed X2/X3, I do not want to do a clean install of X1.
 
I still have folks I help who are on X1 and would otherwise blow this off completely, but for the life of me cannot recall how to bypass this... the X1D Expanded patch is the only one that will run (since the program is already there), but even entering the expanded S/N on that patch, the pop-up in SONAR has the original S/N from the plugin reload (and cannot be replaced).

If you were going to install Sonar X3, you didn't need to install X1 or X2.  Just the FX or Instruments that didn't come with Sonar X3. 
 
Sonar X3 already has the fixes for X1 and X2 included in it. So, you should have just installed X3 and then perform a custom install for X1 and X2 for the instruments or FX you wanted from the software that are not in X3, but not Sonar itself. The Basic instruments are still in Sonar X3, however, for specialty Instruments, the registration code is in your account page on the Cakewalk site.
 
I hope this helps.
 
 

If you were up for it you could edit the registry but it might be quicker to just bite the bullet and call tech support.

Thanks for the replies. I remembered this as soon as I triggered it, but had already loaded up through X3 before I got everything back online. In reality, this is not a big deal, since X1/X3 will pass cwp's back and forth without issues; the only real caveat being that I need to remember not to insert a VST3 plugin (in X3). Pulling those files open in X1/X2 gives the "Missing Plugin" screen and does not allow for replacement.
 
I haven't tweaked out preferences fully in X3 yet, but imported absolutely nothing from anywhere and this machine is running in the happiest place it has ever been. I will need to make a post on what I did with this rebuild (had been running for 4 years before I just reformatted it) because I made a specific effort on this build to kill every latency offender that hit my radar (and has essentially none now with "full use" - internet/IE open, virus scanner online, X3 running, etc.).

Quick update in case anyone catches this thread in the future (I hate to leave loose ends). The solution is to search the registry for the X1 (initial) S/N and replace it with the X1 Expanded S/N. Then re-install the X1d patch and the registration pop up (both installing the X1d patch and inside the X1d program on next launch) will function as expected (they are pre-filled with the proper S/N).
 
Be advised (for anyone only seeing this post), that this is for the situation of reloading plugins from the X1 disks after X1d has already been fully installed (i.e. please see the OP).