Any way to automatically update Item Names based on criteria?

I’d like to keep the Item Names of Category A synced to match the value of a particular Item from Category B. I tried making converting Category A into a Primary Key and I can make it work once, but any new items manually added do not stay in sync.
Is there any way to do this automatically via scripting (e.g. I don’t have to remember to press a button every time I want to sync the names up)?