Showing links within same table?

I have a list of product brands that we sell in a single table. Some brands in the table are actually sub-brands of other brands in the same table. I’d like to have two fields liking to this table internally, one where you can select a parent-brand for the record, and the other where you can select a child-brand for the record.

How do I make it so that adding a parent to a child record also adds corresponding child to the parent record?