My grandfather bought a plot with 5 spaces next to each other in a graveyard you can no longer get plots for, thinking him his wife and his 3 boys would be buried there. His did this when the boys were under 10 years old. The ones for him and my grandma are used now, but the three boys are grown, moved away from that small town and with grandkids of their own now and they will not be using the plot.

Let him do what he wants with his money, but he is delusional if he thinks his children will be buried there too.