If you use the class to add data in the global, then you can use the Callback methods. For example %OnAfterSave does what you want.
On the other hand if you put data directly into the global then you will need some way to track when data is added. You can do this by writing your own agent or by doing what is adviced in this post: How can i make copy of a global automatically in my local system? (this is the link referenced in that answer) http://docs.intersystems.com/cache20141/csp/docbook/DocBook.UI.Page.cls?KEY=GCDI_journal#GCDI_journal_util_ZJRNFILT