If you decide to file the G884 first, here is the list of documents you need to include with the COC application. As you can tell by looking at the list, there are still going to be documents you need to include with the application even if you dont' file the G884. And honestly, filling out the form is the hard part. Not providing the supporting documents.
photos - Child
BC – Child (Guatemalan BC)
MC -Parents (if applic)
Divorce decree –Parents (if applic)
Proof of US citizenship - Parents (state BC for each parent or COC if parent was born abroad)
Proof of Legal custody - Child (Protocolo)
Permanent Resident Card (Green card) - Child
Proof of required US residence - Parents
Final adoption decree - Child w/Parents (readoption paperwork)
Evidence of legal name change - Child (& Parent if applicable)
Also ANYTHING in SPANISH, must have the ENGLISH translation copy included, like the Protocolo, etc