I'm also a descendent of William Letts from Holland Netherlands (b 1642 and d 1701 in Perth Amboy). I would love to hear about anything you have found out over the years...I've just started researching this line which goes down to my grandmother Doris Letts and her parents Earl Letts and Edith (Kivist) Letts. The entire line is from South Amboy with the exception of William Letts who lived originally in Elizabethtown, East Jersey.
My email is firstname.lastname@example.org
Anything you could share would be appreciated,