Visitor visa for parents after adoption

My son went adaption at the age of 16 to my relative. That time he has leagly changed his name and family name, so that his passport and other educational documents will have my relative name as father and mother.

Now He is in STUDENT VISA, Phd Student from US university and working on EAD with Good salary 8K per Month.

In his Birth certificate my name and my wife name mentioned as Father and Mother and his old name will be there. There is a registered legal Adoption document which hold our names and relative name who adopt him. and Advertisement for name change in Newspaper. Now he want us to visit USA and he is supposed to sponsor us.

Can he sponsor us for Visitor Visa (Visitor visa). If so What he has to write in Inivitation letter. How should he mention us ?. Kindly help me in this regard.

He can sposor your visa.

He can say that he wants to invite his biological parents to come and visit him.