The mechanics of the succession to the throne are never indicated in Egyptian sources. It is generally assumed that the eldest son of the king by his queen was the likely successor, but a more ambitious and politically competent son by a minor wife might have proven succesful. This lack of a clear law of succession appears to have led to various harem conspiracies, of which only a few are known. During Dynasty 12, the post of coregent was established whereby the designated successor was crowned as joint king during his father’s lifetime, but even this procedure did not prevent an un successful attempt to dispose of both Amenemhat Iand his coregent, Senusret I, in favor of a rival candidate. During Dynasty19, the post of crown prince, or iry pct, was created, but this too seems to have lapsed during Dynasty 20. It is a curious fact that royal princes are rarely attested during the reigns of their fathers except during the later period of Egyptian history.
See also Harem Conspiracy Papyri.
Historical Dictionary Of Ancient Egypt by Morris L. Bierbrier
Ancient Egypt. A Reference Guide. EdwART. 2011.