Thanks for your posting, I saw the info, and sent a message to the curator of the tree in the US, but no response yet. I am not sure if it is still followed or not.
On another note, I might be travelling to Nymburk this year, to see the place where our branch of the Czerny family migrated from. Do you think there is a good chance to find traces of the family in the church registrars? Is it a usual thing to approach church officials and ask to open these documents for me?
There has been a longstanding story in my family of a family relationshi. My Great Great Grandmther was nee Czerny. The family comes from lower Bavaria maybe 150 miles from Vienna. The relationship is plausible probably a cousin but I don't know the family tree and people more knowledgeabl have passed away. They did reportedy have music written and signed by Carl but I don't know how uncommon that would be.