Ah, the Twilight Zone! This lady had no belief that prayers for those who have passed on had any purpose. She heard testimony that had her questioning her conclusion. She simply acted on the idea that perhaps her father-in-law was trying to communicate with her and that he wanted prayers. So she acted. She prayed.
Who do you believe was 'manipulating' her to pray, and how did her praying for father-in-law benefit anyone else but her father-in-law? I am positive it is not scriptural that someone can "steal" someone else's prayer and then use it for their own benefit!
Nope, not "using" her prayer in any way, leading her away from Scripture and truth. There is absolutely nothing in Scripture that supports the idea that we are supposed to pray for or ask dead ancestors to do anything for us at all. Think of this, if we could actually effect the existences of dead ancestors through prayer, don't you think Jesus would have bothered to mention it? Something that important, such a radical departure from Scripture and all known ways that God deals with man, you'd think He would have said something. "Oh, BTW, when you're praying, don't forget to pray for your Father-in-law, because otherwise he's going to spend extra time in Purgatory until he figures things out. You can help get him out early on parole". No, Jesus said literally nothing, and the Law that he revered said nothing about it either. None of the early church Fathers said anything about it. Given all of that, why do you assume something that was so radically different and added long after the Church was founded has any authority at all?
Luke 16:
24 “Then he cried and said, ‘Father Abraham, have mercy on me, and send Lazarus that he may dip the tip of his finger in water and cool my tongue; for I am tormented in this flame.’ 25 But Abraham said, ‘Son, remember that in your lifetime you received your good things, and likewise Lazarus evil things; but now he is comforted and you are tormented. 26 And besides all this, between us and you there is a great gulf fixed, so that those who want to pass from here to you cannot, nor can those from there pass to us.’
No mention of purgatory, no mention of even the idea that one's time can be cut short anywhere. In fact:
Hebrews 9:
27 And as it is appointed for men to die once, but after this the judgment