Areas of Germany that are now in other Countries after WWII

My Hanke-Rosner connections were variously in Germany, Austria and now Poland & Czech Republic respectively. (The towns didn't move, just the country names). How does one research that? My GGrandfather Albert Hanke was born in Lindeweise, Schleisen, Germany (Breslau area)in 1858 and my GGrandmother Franciska (Frances) Rosner (Rosener) was born in Leshan, Schleisen, Germany in 1863. He considered himself German and she considered herself Austrian. He came to the US in 1881 and she in 1887. They met and married in Jericho, Calumet County, WI.