John,

Well, if you're already in touch with the folks at the ADM, that's your best possible source. The only other possible avvenue is locating a better resource on NY ship manifests during the Loyalist emigrations in 1783-1785. Don't forget to search on Everit and Averit variants as well as the others for Everett. I have found Handspiker variants in the dozens, with a recent one being Vandlespiker, so, sometimes we have to be creative or "out of the box" when looking for tough to find answers.

Jared