Dont take it bad im just teaching u basic things . I m taking your names in some other post becasue ur a good example, nothing personal .
There has always been paper called " invitation" used by companies to participate in conferemces , meetings mostly for scholars like me (phd) and since 2007 or so you dont need to physically carry it on interview unless ubr asked {rarely》. But for personal visits you dnt need invitstion or so called sponsorship . Is ther anything i can help u today¿