Some neat attachments for you.
I will take this page down after you let me know that you got the files. There's realty tax mapping feature in the county that lets anyone search for landowners.
There's a 1963 page from his college yearbook there, too.
The obituary from The Trenton Times shows that Ian died in Princeton, NJ.
Short obituary for Susan Bates MacMillan -
http://www.legacy.com/obituaries/nytimes/obituary.aspx?n=Susan-Bates-Mac...
Also land donated in memory of Susan Bates MacMillan and her father. --
http://www.lakevisit.com/biking.html
youtube.com about donated falls -
http://youtu.be/K1ieqmWsoE4