I found a Hornung & Møller piano for sale in Salt Lake a few weeks ago.
I looked inside and found the serial number.
Then I was playing on the State Archives site for Denmark and found the Nummerbøger fra Hornung og Møller. Naturally, I had to look up this piano that is now in Utah.
Hornung og Møller Nummerbøger 1919-1934 opslag 84
Then I found one in an auction. It's serial number is 40410.
Hornung og Møller Nummerbøger 1934-1960 opslag 6
It was built 15 Dec. 1934 for Kirsten Free Hendriksen of Nørregade 50 in København. It is also a Rococo style. And of course since I had a name, I had to check the census.
1930 Folketælling København Nørregade 50 (Nørregade lige nr. opslag 547)