Let's say an elderly man needs to be cleaned: he cannot clean himself because of extreme weakness. Can his daughter do this or must she hire someone else?
The torah sometimes uses the word "uncovered his nakedness" to mean relations (absolutely not the uncovering of the body) (not forbidden to see your father naked)
When a person has promiscuous relations with a woman and conceives a daughter with her, that daughter is considered an ervah for him. Although the Torah does not state: "Do not reveal the nakedness of your daughter," the prohibition is of Scriptural origin. Since [the Torah] forbade [relations] with the daughter of one's daughter, it did not mention [the prohibition against] one's daughter. This is not from the words of our Sages. Therefore a person who has relations with a daughter born of his wife is liable for two [sin offerings], for [relations with] his daughter and for relations with a woman and her daughter.
A person who inserts the corona into [the woman's vaginal channel] is referred to as one who "uncovers" as [Leviticus 20:18] states: "He uncovered her source." A person who inserts the entire organ is referred to as one who completes [intercourse]. With regard to all the forbidden relations [mentioned] by the Torah, one who "uncovers" and one who "completes [intercourse] are [equally] liable for execution by the court, kerait, lashes, or stripes for rebellious conduct. Even though the man did not ejaculate and even if he withdrew and did not complete relations, [the man and the woman] both become liable. Whether a person engages in vaginal or anal intercourse, when he "uncovers" [the woman], they both become liable for execution, kerait, lashes, or stripes for rebellious conduct. Whether they were lying or standing, liability is established by the insertion of the corona.
What is implied? A father is permitted to embrace his daughter, kiss her, and sleep with her with their bodies touching and a mother may do the same with her son as long as they are young. When they grow and become mature with the girl's body becoming developed, they should each sleep in clothing.
If the daughter is embarrassed to stand before her father naked or she married, and similarly, if the mother was embarrassed to stand before her son naked, even if [the children] are minors, when one reaches the point when one is ashamed [of being naked] in their presence, they should sleep together only when clothed
It is forbidden for a man to have any woman - whether a minor or an adult, whether a servant or a freed woman - perform personal tasks for him, lest he come to lewd thoughts.
Which tasks are referred to? Washing his face, his hands, or his feet, spreading his bed in his presence, and pouring him a cup. For these tasks are performed for a man only by his wife.
[A man] should not send greetings to a woman at all, not even via a messenger.
A person should not enter a bathhouse with his father, his sister's husband, nor with his student. If he needs his student [to assist him], it is permitted. There are places where people followed the custom that two brothers would not enter a bathhouse at the same time.