Yours is a question I had while I awaited my FBR approval. I've watched this discussion since I applied in April, and occasionally someone would post that they were asked for additional documents, but they usually never explained why.
Recently,
jpauls had an issue because he did not originally send long form birth certificates, which were probably missing the names of the parents:
jpauls wrote: ↑Mon Nov 05, 2018 1:20 pm
Woke up to an email from DFA. Apparently mine and my mom's birth certificates are the abbreviated version. I'm confused because in the US these are considered the long form birth certificates.
After sending in the long form,
jpauls pretty quickly received notice of citizenship approval. BTW, I live in the US, and when I requested birth certificates, I didn't have to do anything to obtain the long form.
Someone else forgot to have his photos notarised/certified.
I think if you send them everything they specify, you won't have any further requests. That means original, long form certificates, properly witnessed and notarised documents. And everything should tie together without raising any serious questions. When you think about it, every document supports another document. For example, your grandparents marriage certificate contains their names as well as your great grandparents names. Your grandparent's birth certificate also has his/her parent's names. So it shows that both certificates are for the same person. So if what you provides documents an unbroken chain, I think you will be successful.
I believe they allow for some discrepancies. Dates may not be exact, for example. The ages listed on my grandparents marriage certificate were incorrect. But that did not result in any questions to me from DFA.
Or maybe your great grandmother's name on your grandparent's birth and marriage certificates is somewhat different (e.g. "Elizabeth" on one and "Lizzie" the other). My grandfather had a middle initial on his death certificate that appears on no other document. Again, my application was approved with no request for additional information or documents. But if your parent's birth certificate names his/her parents as "Michael Shea Margaret O'Malley", but his/her marriage certificate names "John Murphy and Ellen Horan", that would surely be a red flag.