Updating the list of "orphans" in my family history, I realised that the name of Marie-Luise Stohlmann / Stolman is actually rare and thus a promising lead. Today the name is concentrated in the area Herford / Lippe / Minden-Lübbecke, which is where Marie-Luise Stohlmann lived.
I understand from this ancestry list that the name line goes back to Johan Christoffer Ernstmeier (1698-1772) who obviously married into the Stolman family and farm at Klosterbauerschaft (near Herford) and took on the name. (He's generation 6 of the list, so there are 5 Ernstmeier generations before him.) Among his children and grandchildren there are several males who would qualifiy as grandfather of father for Marie-Luise Stohlmann, so if anybody could help me to fix this gap, I'd be very grateful.
Further details: Marie Luise Stohlmann married Carl Heinrich Schilling, their daughter Luise Schilling was born 1841 in Neesen and baptised in nearby Lerbeck (both places have merged into the town Porta Westfalica).
Further Stohlmann names from the same area are here though not sure how they relate to the others mentioned above.