According to the registry books is possible that Vilém Sedláček was born September 7, 1848 in Bělčice in the house No. 53. http://digi.ceskearchivy.cz/cs/2093/74
, third from the top, it is Bělčice - Book 6, born in 1825-1857, (Roman Catholic Church).
According to the registry books, it is possible that Vilém Sedláček had a wedding in Bělčice house No.20 with Anna Lázničková on January 20, 1874 http://digi.ceskearchivy.cz/cs/2098/44
, first from the top, it is Bělčice - Book 11, devotees in 1847-1896 (Roman Catholic Church).
But in the Czech registry books is, in these two entries, any note that he traveled to the USA. I was not looking for his children. You need to find the children, so you should be sure that this is William. Good luck!