Best practices for tagging branches

Some cafés or restaurants have a few branches. I'm not thinking of major franchises like Subway (for that, see this question) but of examples like The Barn in Berlin, a small coffee shop chain with 6 locations in town.

Currently when searching for The Barn in Nominatim, ony a couple results come up, and they're all named the same. This could hopefully be improved with better tagging of branches.

A good start is definitely to use the wikied branch tag with the name of the branch. For example:

name="The Barn" branch="Neukölln"

But other than this: are there other tags that could be used in combination to improve the tagging and interrelation of branches?

• chain has only been used 40 times but might be useful to indicate that there are other branches of an amenity
• Could there be a tag to specify that this is the chain's original location?
• Other ideas?