I will Pay for my dad's trip, do I attach documentation?

Hi, I am a Colombian national and a U.S. resident. I just processed my visa successfully in the U.S. , now I need to process my dad's visa, who is a Colombian national living in bogota. In part 2.7 of the form it asks who will pay for the trip. When we fill "daughter" in this space, do we need to attach my bank records?

Additionally, do we really need to purchase the flight tickets ahead of time? It seems like a big problem in the case that the visa is denied. Any suggestions on how to get around this?

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