Birth certificate for parents' green card

[GC for parents]

Hello

Both my parents have birth certificates but the names of their parents (parent's parents) are different on the birth certificate than that in the passport due to the indian suffixes. In India it is customary to add 'das' 'bhai' 'kumar' etc to the father's names. My parents' parents are deceased. What type of affidavit or certificate would be required to prove that 

1. NAMEbhai and 2. NAMEkumar are the names for the same persons for my parents parents.

thank you 

[pontevecchio]

Why would their parents names be relevant? Just file the forms and wait for any specific documentation clarification needed.

[GC for parents]

Thank you Pontevecchio. Wouldnt the name of the grandparents in the passport and that on the birth certificate need to match for the parents GC to be processed. 

[pontevecchio]

They are migrating based on your sponsorship. You need proof that these are your parents. Your Grandparents have no role. Push comes to shove, they will ask you to consider a DNA test for parentage.