Sponsorship/Proof of Relationship

[IT applicant]

Hi,
This is regarding the sponsorship of parents.

I don't have my birth certificate available to showcase the relationship proof. I tried getting one from the place I was born but they don't have the records available.

Has anyone tried any alternate means as a proof of relationship and been successful.. e.g. your passport (country of origin passport if it has parents name) or academic marksheets.

Please advise

thanks,