Change in plans again! We go to Lindenkeller instead.
A reserved a table "upstairs". That is: outside but with regular restaurant service (italian food). They said there's also plenty of space "downstairs" , tough, which is the regular biergarten with bavarian snacks so we can decide on location what we prefer. Apparently you can order food from the restaurant in the biergarten as well.
For new guests: Just look for the little meet-up sign on the table ;)