So glad you found the tombstones of your ancestors in the Greenwood Cemetery.
I have been to the Flesherton Cemetery where your other ancestors were laid to rest.
I am presuming you have not yet been there.
Here is a death notice you may or may not already have for Thomas Whitten of Flesherton :http://news2.ourontario.ca/1124896/data?n=6
Looking forward to hearing about your visit to the Flesherton Cemetery.