Have a US trademark application that has been granted a Notice of Allowance in multiple classes but you're not using in all of the classes? Want a registration in the classes where you have use?
In this type of situation, you can split out the class(es) of goods where you don't have use by filing a "Request to Divide." Then, upon dividing out the classes without use, for the classes where you do file the Statement of Use the USPTO will issue a registration. The remaining class(es) of goods that were divided out will have been assigned a new serial number, separate from the "parent" application. Down the road when you have use with the goods/services covered in the new application, you can file another Statement of Use and a separate registration will issue for those classes.
So, rather than an updated registration, you would have two registration certificates covering the mark in the respective classes.