The person to be inherited or succeeded, may organize the identity of the heir by appointment. It would be a testament, effective only at the moment of death and reversible before that, or it could be irreversible designation already long before. In the law, a will or testament is a documentary instrument by which a person regulates the rights of others over his property or family after his death. ...

Depending on the culture, traditions and laws, the appointment could be sufficient as itself, or it may need some strengthening (justification), acts such as adoption or marriage. Adoption is the legal act of permanently placing a child with a parent or parents other than the birth parents. ... Marriage is a relationship and bond, most commonly between a man and a woman, that plays a key role in the definition of many families. ...

For example Roman Emperors designated often their successors by adopting, which had been an established legal Roman practice long in pre-imperial eras. Cf particularly Nerva, Trajan, Hadrian and Marcus Aurelius. Roman Emperor is the title historians use to refer to the ruler of the Roman Empire. ... NERVA is also an acronym for Nuclear Engine for Rocket Vehicle Application, part of a NASA project to produce a nuclear thermal rocket engine. ... Emperor Trajan Marcus Ulpius Nerva Traianus (September 18, 53 - August 9, 117), Roman Emperor (98 - 117), commonly called Trajan, was the second of the so-called five good emperors of the Roman Empire. ... Emperor Hadrian Publius Aelius Traianus Hadrianus (January 24, 76 - July 10, 138), known as Hadrian in English, was a Roman emperor from 117 - 138. ... Marcus Aurelius Imperator Caesar Marcus Aurelius Antoninus Augustus (April 26, 121 – March 17, 180) was Roman Emperor from 161 to his death in 180. ...

Marriage of female relatives, particularly daughters, to desired successors has been utilized by persons to be inherited throughout civilization to organize one's own succession in a way where a ruler may practically appoint his successor. Appointment can be masked by creating and utilizing a right where a female in entitled to have her husband to succeed.

Father-in-law succeeded by son-in-law is obviously not a female succeeding a female: the monarch chose his successor, and formalized that appointment by marrying the chosen man with a royal daughter, which also worked as a way to legitimize the succession.

A monarch strengthens his position by marrying a princess of the (previous) royal family. And having his Crown Prince and some other children born of that woman. This could even be maximized: a king marries a number of royal princesses, and tries to have children with as many of them as possible.

Marriage was a way to legitimize succession for example by Pharaohs in ancient Egypt, as well as in China. This article refers to the historical Pharaoh. ... The Great Wall of China, stretching over 6,700 km, was erected beginning in the 3rd century BC to guard the north from raids by men on horses. ...

Inheritance Monarchy Agnatic seniority Matrilineal succession For other uses, see inheritance (disambiguation). ... For related meanings see also Monarch (disambiguation) A monarchy, (from the Greek monos, one, and archein, to rule) is a form of government that has a monarch as Head of State. ... In hereditary monarchies, particularly in more ancient or in more underdeveloped times, seniority was a much used principle of order of succession. ...