Correspondent bank is like a delegator in a country to operate on behalf of the delegatee who doesn't normally has established business in that country.
However, I heard that for some bank groups, one subsidiary can be the correspondent bank for another subsidiary, especially in the area of clearing. Let's say Deutsche Bank Italy can be the correspondent bank for Deutsche Bank North America.
Does it imply that Deutsche Bank Italy can hold a Nostro account in Deutsche Bank North America or vice versa.
I wonder why would these kind of relationship considered as correspondent? What are the limitations/benefits for banks operating in this way?