What documents would a Nicaraguan need?

So my fiancé is Nicaraguan and we plan on getting married and applying/petition/ begin the green card process . In her country she needs to "apostate" her birth certificate. Does she need to do this or can she just use her old birth certificate or be able to any other documents like visa,passport, or anything else, and if anyone can send any type of website with information relating or informative knowledge would be great. She deosnt live with me at the moment although she visits and lives with me when we can so she is out of the country most time . Don't know if that would be need?? And could we print these documents out incase she's out of her home country as a copy and would it be valid? Thank you for taking you're time to read and possibly commenting