What is the ruling on a father registering a plot of land in his daughter's name after receiving its price from his son-in-law, and is it permissible for him not to register it until after his death, and what is the ruling on registering the land at its price at the time of sale or at its current price?

If the sale was valid and you paid the price, the seller is obliged to hand over the sold item to the buyer and relinquish his possession of it. This is because a sale, when it fulfills its conditions, transfers the sold item to the ownership of the buyer. The written documentation of the sale in official papers is for authentication purposes only. The father-in-law's procrastination in handing over the land is unlawful (haram (definition)) according to Islamic law, because it constitutes usurpation (ghasb). The Prophet, peace be upon him, said: "Whoever takes a span of land unjustly, will have it encompassed around his neck from seven earths." It is not permissible for him to register it in the name of his daughter or anyone else except with the buyer's willing permission. The questioner's right is to the land he purchased, not its value.