I have corresponded with Thierry Dormoy, who posted the original query on this board. Sorry to say, we haven't found common ancestors yet. However, Thierry connected me with another French researcher who has Gaasch blood through a distant ancestor. Our families come together in the mid-1700s.
In my family, six siblings emigrated from Bettembourg, Luxembourg, to Minnesota. Franz Gaasch arrived in 1881 and lived in Winona, Sleepy Eye and then Morton, Minnesota. He was joined in Morton by John Peter Gaasch in 1887. "Pete" visited Luxembourg in 1899 and returned with the remainder of the family: Anna, John, Margaret and Mary Ann.
Franz married Mary Ann Clancy; they have living descendants.
John Peter married Mary O'Toole; they have living descendants.
Anna and John did not marry.
Margaret married Albert Kumro; they had no children.
Mary Ann or "Jenny" married Gus Miller; they have living descendants.
The Gaasch men were wagonmakers in Luxembourg. In America they adapted as carpenters and lumber yard managers. Descendants are scattered, but a core of us still live in Minnesota. Feel free to contact me directly for more data.
joe_ehleringer@yahoo.com