In scenarios where you need to push a new office to NRDS for an existing member [using the Membership Application Wizard is not an option], you'll need to do the following:
Once you've created the office/account record and added an office membership record for this new office, you must open the office membership record, click the "Run Workflow" button at the top of the page in the ribbon toolbar, select the "Generate NRDS ID" option, and click OK.
Please see the screenshot below for an example.