Create a single list of negative keywords that can be applied to campaigns within an MCC.
According Ginny Marvin's report, Google has quietly added another perk for Managed Accounts: the ability to create and share negative keyword lists across accounts.
Maybe you’ve been laboriously adding the same lists of negative keyword accounts manually or using a script to automate cross-account negative lists. Now, for accounts in a managed account (formerly My Client Center, or MCC), you can set up a negative keyword list in the top-level Shared Library that can then be associated at the account level.
Once you create a manager account-level negative keyword list, you’ll need to apply it to campaigns at the individual account. Manager account-level lists show up in the Shared Library of each account with the label “Shared from a manager account.” Just like any other list in the Shared Library, click the check box next to it to apply it to campaigns within that account.