I still have not found a connection but I have found some info for you - go to Texas genweb and search the surname Haardt - I found a bunch for you in Harris County while searching for me!
Otto Herman Haardt III and Rita Tunnell gave birth to Otto Herman the IV on 11-18-1949
There is also a Nita Annette Haardt b. 5-26-1952 and Charlie Newman Haardt b 2-16-1954. They quit listing parents after a certain year but if these are not the children of Herman and Rita they are probably related.
There are several deaths - divorces etc - here are just a few
Otto Herman Haardt Jr died 6 April 1972
Louise A Haardt died 22 Apr 1988
Judy Kay Haardt 18 Nov 1990
Go to Texas genweb- click on surname search - then go down the page to where you can click on county and surname - for older information (not picked up by surname general search) you have to go to the county website and look at archives, etc
Email if you need help manuvering the genweb