I have a question about Frisian language, or rather a sir name derivation. I have an ancestor, Jakob Miller, from Holland, who immigrated to PA in the early 1700s. Miller is a Dutch name?
His family passed on blood dyscrasia which now infects a fairly large percentage of the population. It is fairly mild and many people never even know that they have it, until they bleed out on an operating table during a routine procedure.
I've read that a number of US German families named Mueller changed their name to Miller due to persecution during WW1 & 2.
The Netherlands is a mixture of Dutch, Flemings, and Frisian with Frisian being currently spoken in a small northwest portion of coastal Netherlands.
Miller does not sound like it would be an extraction of any of those but Jakob, of course, does.
It is possible that Mulder (Dutch: Miller) or Mueller (German: Miller) were changed at some time in the past.
The coastal Dutch were directly across the channel from England and were great traders. Sometimes the contact with the English caused them to Anglicize their names for business reasons.
It is also possible if they came to America on an English boat by way of England the name change could have happened there.
Another possibility is that Jakob was of English extraction whose family had immigrated to Holland sometime in the 17th century. That happened pretty frequently because of the religious wars in England at the time.