Seeking Austrian Property Declarations by Haas family for piano

Good Evening ... I am a piano technician and piano researching trying to determine the provenance of a Petrof Grand Piano built in 1910 in the Czech Petrof Factory and shipped to a warehouse in Vienna. This piano is located here in South Carolina and may be a war trophy, looted, auctioned or brought to the US legally by the owner. It is an unusual find since Petrof did not export pianos to the US until the 1980's. The Nazi authorities annexed Austria in 1938 and all citizens and families where required by law to list their possessions including real property, art work, jewelry, furniture, musical instruments , antiques, securities, coin collections, sculptures , bank accounts.  Claims filed after the war often only had an instrument name such as Steinway, Erard, Pleyel, Bechstein, Bosendorfer with no serial numbers . Paperwork was lost or could not be located and without proof it was almost impossible to get a piano back. Only one Petrof Grand Piano claim is listed in missing property files and that was for a piano owned by Grete Haas left in her mother's custody when Grete emigrated to the US. Correspondence shows that in 1946 it was in danger of being confiscated to make room for displaced war victims.

The Haas family consisting of Grete, mother Anna and father Frederich are listed on microfilm a filing declarations. I need someone that can access this microfilm at College Park to see if any Haas family members listed their piano and serial number. At the same time perhaps a researcher can see if they can scan other declarations for pianos and serial numbers noting who filled the forms out. I am looking for the owner of serial number 24035 but recently found another picture of serial number 22910. Both of these pianos have the name Ant. Petrof in large letters on the fallboard that closes down on the keys. The Haas piano could be either of these two pianos or an entirely different one.