I agree with the other members re the obtaining of the original birth certificate!
I purchased the original birth certificate, of an adopted child, she already had the adoption papers, with very little details on it, we found 4 close registrations so ordered them all at once online. They all arrived together with no problems at all.
As long as you have registration detail's and year of birth you do not need all the other info on line,
From memory they ask is this an adoption, do not tick yes, it is not an adoption but the original birth.
This was a wonderful result for this family as mother and daughter were reunited just this year.
Order on line.
Good luck
Suzy