Are the actions of the uncle considered theft from the heirs of his deceased sister by dividing the inheritance with the paternal half-siblings without the knowledge or consent of all full-siblings, and what is the ruling on exceeding one-third of the estate in this division?

The deceased's estate must be divided according to Allah's law, not according to the uncle's wishes. Half-brothers from the father's side do not inherit when a full brother is present. If the uncle gave the half-brothers from the father's side anything from the inheritance, he has transgressed Allah's limits and encroached upon the heirs' share. He is responsible for what he deprived them of. If the mature and sound-minded heir pardons him, it is permissible. However, if the heir is not mature or sound-minded, then his right must be guaranteed. The matter of the one-third (of the estate) has no relation to what the uncle did.