You can use Mayday HQ to create new Accounts in your CoA across the group all in one go, so you no longer need to go in and out of each Xero file and create them one by one.
First, choose the "Create new account" button in the top-right:
You can then fill in the details and save any changes:
Clicking "Save Accounts" will create that new account in each of your Xero orgs.