My name is Andre Thesing from Holland. First of all I like to say that you´re very lucky to be a Thesing! I also congratulate you´re partner that he/she has catched such a Thesing like you are.
My father has searched, and found out much information about Thesings. He has traced untill ( I believe) 1760 in Dissen Germany. He also had knew the names of ancestors who went to America. Unfortunatly he pasted away so I cannot ask him but I have his documents overhere.