Historical Documents

Dass wondering about the authenticity of two historical scriptures

1) Dhan Dhan Guru Gobind Singh Sahib's 52 Bachans

2)Sharda Pooran Granth, Dhan Dhan Bhai Mani Singh Sahib Ji

Is there any historical proof of their authenticity?
Has Dhan Dhan Bhai Sahib Randheer Singh ji quoted from any of these two documents?

Dhan Dhan Bhai Sahib Randheer Singh ji, we must avoid that "Dhan Dhan", I think.

Dass was hoping the more respect he showed to Guru Sahib and his Gurmukhs the better chance at getting darshan one day Forgive me for my mistake