Is it permissible for the questioner to build a house with his own money on land inherited from his father, and register the house in his own name, while reserving the right to build upper floors for his siblings with their consent?

The inherited land is a right for all heirs according to their prescribed shares. If the adult, mature heirs permit you to build on it, there is no harm, due to the Prophet's (peace be upon him) saying: "Conciliation is permissible among Muslims, except for a conciliation that forbids what is lawful or permits what is unlawful. And Muslims are bound by their conditions, except for a condition that forbids what is lawful or permits what is unlawful."