How do i modify multiple files at the same time?

Let’s say i have to enter someone’s name and SSN along with his adress in multiple documents along with his adress.I want to enter it once,and for it to be updated in all the documents in the same folder without me opening them.
I tried to wrap my head around master documents but i didn’t understand much.
I would really appreciate it if someone could give me a helping hand.

Use a table (Calc or Base) to enter your data, create a query and use the “mail merge” feature to replace a Writer’s document fields (drag&dropped from the database beamer into the document) with the chosen values.