What a nice surprise to see your message today.
Fuerstenhut 9or Kniceci Plane) is indeed a little town in Bohemia. The surnames you mention are in my family tree although I cannot say much about their ancestors. Joseph and Rosalia Feature as such. The other two names are there but not the same individuals - may be related though!
Taking a wild guess here, did your coworker's ancestors settle in St Paul / MN ?
Sadly I had to take down my ancestry homepage. Therefore I now send out copies of part of my tree by email attachment.
Please feel free to contact me by email on maresliatbtinternetdotcom and I will be more than happy to share what I have.