I got it to work without having to restart or reinstall.  Both clients must be running and all operations are done from the console.  In the nu client, type

walletlock

Then completely unlock the wallet.  Place your passphrase inside quotes as noted above.  600 second timeout should be plenty of time to complete the process.

walletpassphrase "**************" 600

Now repeat the above two commands in the B&C client.  The next command imports the NuShares wallet.  I had to specify the complete path to the wallet, eg. /home/username/.nu/walletS.dat, where username is the unique login name (This path is for a typical Linux setup; Windows will be different).  The last field is the password, again enclosed in quotes:

importnusharewallet path-to-wallet-file "**************"

The Blockshares should appear in less than a minute.  One can then unlock both clients for minting only as usual.