OP: You didn't miss anything. I applied for the Citi Reserve earlier in the week and was talking tonight with my wife that there was no place to put in my current hilton account #.
Hoping the merge account function on the hhonors website works.
Btw; how long did it take for your card to arrive? Waiting on my card to book our flight, and when it closes, to use the free weekend night certs.