I think the key word here is "supposedly" in regard to when several of Ulrich's children were born. I think that someone made up the dates without looking at the ages of the parents. Ulrich's wife Anna was born in 1720. The earliest birth(Elizabeth) is shown as 1740 with the next birth(Ulrich III) not until 1751. It seems likely that some of these children were born between 1740 and 1751 and even more likely that just as many were born in the 1750s.
If anyone has any documented information concerning the birth dates for the children of Ulrich(other than Elizabeth, Ulrich III and Michael), please let us know.