I'd been holding off combining accounts since I wouldn't need anything from the SPG side until LTPP looks at combined nights at year end. And I was afraid of adding complexity or a new source of new issues. But nothing else was updating my LT status, and I want the status for a stay in a few days, so I decided to give it a go, hoping the merging would force the system to recalculate (or in my case, calculate) lifetime status.

Much to my surprise, it all worked perfectly. The accounts combined without error, the YTD and lifetime nights are correct, now showing the MR+SPG totals, and lifetime elite years is likewise showing the correct total. My lifetime status was immediately updated to LTP, and my current status also bumped up to Platinum.