On one side Bhai Gurdaas Jee , Baba Nand Singh Jee maharaj, Bhai Sahib Bhai Randheer Singh Jee who never had doubt on waheguru as a GuruMantar .
On other side is Balbir Singh
Useless to say who I or anyone will believe in ..... Not even worth discussing regardless of how many proof you give by manipulating Gurbani Sahib.