Did you meet our criteria of phase 1 or phase 2?
 
You must have held bitcoin at block height 498,777 and conducted an outgoing transaction between 494,000 and the fork (498,777) to meet phase 1 criteria and receive UBTC automatically.
 
If not, phase 2 criteria is that you must have bitcoin at block height 498,777 and conducted an outgoing transaction between 494,000 and 502,315, which will result in distribution of UBTC on 24 Jan 2018.
 
However, if you do not fulfill both phases then please provide proof of an outgoing transaction from the address that held BTC at 498,777 along with detailed explanation as why you missed phase 1 or phase 2.

Please email to supprt@ub.com for assistance.

Each address has it's own key... so, logically, if you have coins spread across multiple address, you're going to need to get multiple keys. (NOTE: Instead of using 'dumpprivkey' multiple times to get each private key, you can use the 'dumpwallet' command to just dump the whole wallet out to a file).

PROS: Free! Maintains privacy (none of the addresses will be linked)
CONS: Time consuming, messy, possibility of missing a key/address

Or... as Spendulus has suggested, just send ALL the coins in that wallet to a new address in that wallet, and just export that one key for the new address.

PROS: Just one key to rule them all!
CONS: Will cost a transaction fee... which could get large dependent on how many UTXOs you're trying to consolidate, plus you have to wait for confirmation... possible privacy implications