The Recktenwalds must have immigrated to the United States at different times. When did your family come to Iowa ? Another group came to Buffalo, N.Y. A third group came to Perkinsville, N.Y. which was a German settlement. Even today most of the families in Perkinsville have German names and there are many graves with the name Recktenwald. There was a farm by the road to Dansville with the name of Recktenwald on the mailbox. Some of the gravestones at the cemetery are carved in Fraktur. The main families in Hornell were large and the two patriarchs were Charles and Joseph Recktenwald. My father's aunt was married to one of them. The Recktenwalds in Perkinsville must have come to the United States ahead of my family because I am told that my family got off the train in Hornellsville and intended settling in Perkinsville but found work in Hornellsville and stayed there. There is a Joao Rechtenwald (note spelling) in Brazil who is looking for information on his lineage over this same service.
There are international family registries available. I have the Brill family registry for Brills all over the world. It gives the addresses of all the Brills in St. Wendel and Winterbach. There are many. When my cousin visited St. Wendel she was told that many of the Brills were into banking in those towns. She didn't meet any of them.