Lord Holder
The Lord Holder is the ruler of Major Holds and his power is rarely checked. As long as he provides protection from Thread, a basic education (though he may opt not to do this), food, and shelter he basically ensured not to be interefered with. In return he gain labor.
The Lord Holder is responsible for tithing the Weyr that his Hold looks to for protection from Thread. Tithes consist of a percentage of the Hold agricultural endevors or other materials (such as cloth, herdbeasts, or wine). The Lord Holder may have more than one wife, but only his first wife will be the Lady Holder. As a result he may have many childern. Since marriages are rarely secured through love, he may also have an abundance of illegitimate children as well.
Lady Holder
The Lady Holder is the first wife of the Lord Holder. She is responsible for having as many children as she can so as to propogate her Lord's lineage and ensure that it does not die. The Lady Holder is also responsible for the Hold and it's upkeep, food, clothing and healing. She is also responsible for the maintenance of supplies, the upkeep of the dwellings, and the residents.
Steward
The day to day tasks of tithing, economics, and trading are delegated to the Stewards by the Lord Holder. He is also responsible for the Hold's dealings with its vassal holds. It is not uncommon for the Steward to be a relative of the Lord Holder, one of his sons, brothers, nephews, or uncles.
Headwoman
The Lady Holder will delegate many of her tasks to the Headwoman.
Heirs
The Heirs are the sons and daughters of the Lord Holder and his Lady Holder. Though his sons are the only ones eligible to become the Lord Holder after his death, both genders are valuable to him. His sons and nephews are taught in the ruling of the Hold and may either be given the job of assisting the Steward, heading one of the branches of the Hold (such as Husbandry), or becoming one of the minor Holders. The daughters and neices are taught by the Lady Holder and Headwoman. They assist the Headwoman in her tasks and are often used as pawns in marriage to secure alliances with other Holds or to increase loyalty with lesser Holds.