Search for German Ancestors: Krei; Breitsprecher; Friedrich

I am currently searching for any information concerning some German ancestors that came to the United States around 1870. Their name was Krei; Fritz (Frederick) Krei was the father, Sophia Schafer Krei the mother. They came from Mecklenburg-Schwerin and brought 4 or 5 children: Johann (John), Fred, Sophia, Sadie and Maria (Mary). They originally settled around Clayton or Winneshiek County, Iowa (but possibly briefly in Wisconsin) before settling around Wayne County, Nebraska in 1887. They were Lutherans and the children all married and lived in Nebraska, Iowa, Minnesota, and Wyoming. Names that married into the family were Breitsprecher and Friedrich (with several spelling variations from generation to generation) and some family members went on to live near Hot Springs, South Dakota, close to the Black Hills. I'm mostly interested in Fritz and Johann, my great-great grandfather and great-grandfather, respectively. I would like to correspond with anyone who has information on any member of this family. Thank you.