Purchasing a plot for development where the exact location of the plot is not demarcated

Q: Can a plot be purchased in a newly developing area where the exact physical location of the plot cannot be determined? They showed the plot on a map and the roads, other plots adjacent to the said plot, roads and park etc. in proximity to the said plot. They showed us that the area of the said plot and told us that your plot cannot be located now as the demarcation of the plots is not yet done. Is this sale and purchase valid?

Slaughtering an animal for a Jinn

Q: I was reading about those who slaughter an animal for the Jinn. I read that if the slaughtered animal is dedicated to a Jinn or Shaitaan, this will be an act of major Shirk (associating partners with Allah Ta'ala).

I have heard the scholars of Ahlus-Sunnah mention, “There is scholarly consensus that it is not permissible to prostrate to anyone or anything besides Allah Ta'ala. However, without the intention of worship, then this is not outright disbelief (kufr).”

My question is that in the first case, where they slaughter the animal for the Jinn, if someone who did this claimed that it was not shirk because it’s like the example mentioned about prostration, then how would you respond to them?