Just an update on the thread I started... "minor in cancun" Even though I had every possible paper (and copies) I could think of to be prepared to take my minor stepdaughter into cancun.....her passport and visitor's card and customs declaration form (filled out on the airplane) was the only documents that were asked for....entering and leaving cancun. That's not to say that would happen with anyone entering or leaving cancun with a minor stepchild, but this trip sure was a breeze. (BTW we arrived on a wed. at 10:30 am and we were the only flight in the terminal) Even when we go back...soon I hope... I will still have all the paperwork just in case. I sure don't want to take a chance on missing my flight while I am arguing with a Mexican official about who this minor child belongs to!
If the immigration agent doesn't like the child's documents you won't argue with them. If you argue with them it will only make things worse. If the child doesn't have documentation that satisfies Immigration then the whole family will simply be put on the next flight back where you came from and there's nothing you can do about it. I'm glad your trip went off without a hitch.