Fwiffo
first of all, whoever was responsible for the selection of the restaurants. he did an excellent job. btw, I assume your hotel wasn't in the city also, right?
I haven't been to all the places myself, but they come up when the talk is about recommendations off the tourist paths, well done.
none of these places belong to a chain.
e.g. just because the plachutta family runs a few places -
https://www.plachutta.at/. they cannot be a called a chain. all places have their individual charme and their clientele, some overlapping cannot be denied, though.
while not longer in the portfolio, the patron of the family was responsible for one of the first gault-millau decorated restaurants in the 18 - 20 points category. they are a primitive rock in the restaurant scene of vienna.