I am so excited that I'm doing some "jumping ahead!" which we all know isn't the best practice.
Today, through networking on the discussion site of my software publisher, I found the birth records of my ggrandmother and two of her sisters. The records are in Dutch, but I could recognize the dates and the names of their father and mother (my gggrandparents). These are the official records of Eindhoven, which includes Hoogerloon in Noord Brabrant. This is a good lead but not yet proven facts. Another lead would be records of the family's leaving the Netherlands with perhaps ship name and port of arrival.
I have yet to find the family in the arrival ship lists. Family tradition is that they came to NYC and spent 6 months there becoming "Americanized" before moving to Illinois. I don't find the Illinois records either — just the 20th century records in Missouri. But the rest of the family stories do match well with the found records, so I am reluctant to deny their value as pointers.