Hi Debbie,
I trust this family "van Lessen" is from Ostfriesland (East Frisia / Eastern Friesland) - say the area around Emden, Germany which once was part of the Kingdom of Hannover.
Maybe it's worth to contact Mr. Marcus Reichel.
His website is here:
http://www.genealogie-reichel.de/index.htm
scroll down and click on the link "E-Mail-Kontakt" in order to send an email to him.
One of the sources (German: Quellen) mentioned on his website is the following book:
Author: Hermann van Lessen
Title: " Die Familie van Lessen 1689 - 1992" (The 'van Lessen' family from 1689 to 1992)
Publisher: Verlag Sollermann in 1993
Your ancestors may be mentioned in it. Good luck...
Kind regards,
Vera (Nagel), Germany