In the Dillman Family Association, we have come across so many different spellings of the name that we end up trying to collect them all, where possible.
Generally, we find that there are twice as many Tillmans today than there are Dillmans, so clearly the names are distinct, one is not a subset of the other, but some people used them interchangeably historically. As an examply, my original ancestor to Pennsylvania was listed as Tillman on the land grant maps! But marriage and death records were Dillman (and birth in Germany listed as Dillmann).
Unfortunately we can’t directly answer your question at the moment. We are in the process of collecting all the migration records available (roughly 86,000). We are still in an early phase or sorting through them all. At some point, hopefully in the next year, we might have a clearer picture.
Indeed we have seem many migrations from the Netherlands for both Tielemans and Dielemans. Where they came from before the Netherlands, isn’t so clear at the moment.
