They would be platies (to the best of my knowledge). Tetras are egg layers so she would have noticed the entire tank bottom being covered in eggs. As for the others, I'm pretty sure they are not live bearers, and since there was instantly (more or less) fry - my educated guess is platies. Platies are also hard to tell if you have males or females.
Good luck with your fry. Do you have fry food or are you using crushed adult food? Also, make sure you keep the tank really clean (which I guess you should know since you've had fry before).
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Phishie

"An ounce of prevention is worth a pound of cure."