Hoping someone has the answer to this one. My Sister-in-law will be coming with us to PV. She was born in Mexico so she has her birth certificate issued in Mexico. She is a US citizen and has her citizenship papers and valid drivers license. She does NOT have a passport. i was told that these papers were okay. Will the paperwork listed above be sufficient. I want to be sure that we do not have any problems. Any help would be appreciated. I was born in US and travel with license and birth certificate all the time, but I was concerned since she is somewhat different.