Hi,

I had a personal and business US Bank card and cancelled the personal one. But I had points and a reservation (couldn't rebook as the category was changed and it was now 70k vs 50k). While talking to a CSR I was told they could merge the account but I would need to wait until the CC drops off .... waited a couple of month ... CC dropped off and asked the CSR to merge the account. He did so and confirmed the points were moved.
Back at the computer I noticed that he was correct that the points were merged but the reservation wasn't. It was still at the old number (which I couldn't access anymore after the first day) with no status and could not be shown (system wanted me to log in which was not possible any monger). Called in and they said they could not change the rewards number but email me the reservation and put a note in there that I'm gold (and that I should just show my card when checking in)..... not really what I wanted to hear. Took me several emails to get this sorted out (I had to escalate it after a while).

So if you plan to merge accounts (as RR creates a new one for every card) make sure no reservations are attached.