Thank you for your question, Steve. Because your research has reached the 16th century, it will be difficult to solve this puzzle. Maybe you can pose your question under the message of Joost Kocken:
http://www.bhic.nl/onderzoeken/forum/bonaerts
All the people who have reacted on this subject, will receive an e-mail with a notification. Maybe they can help you with your research. Good luck!