Although the time-frame may be similar, the Lydia KEILBERG who is my mother's cousin was born in the US, and married in WI. Is it possible that your Lydia was named for ours? We look carefully at any KEILBERG we encounter because it is a fairly scarce surname.
Earlier generations of our KEILBERGs have lived in PA, IL and WI, having immigrated from Burgstadt and the adjacent town of Burkersdorf, Saxony, in the mid- to late 1800's. Other locations for them, and the related families of BERGHANDLER, SCHENK, and FRANKE, are Dresden and "the other Frankfurt." Some of our fellow KEILBERG descendants in Chicago took the surname of their step-father, SCHARF.
Although we do not know of any Netherlands connection, it's still a possibility. We may also be related to some TX KEILBERGs, my current project.
Could you please contact me about the US location(s) for your Lydia KEILBERG? I would be happy to share whatever information might help you. Thanks, Barb G.