girl, Miss, daughter
孃 centers on a young female person: a girl, an unmarried woman (Miss), or a daughter. The meanings are closely related, all referring to a female child or young woman.
孃 combines 女 (woman) with 襄, which likely contributes the sound. The character originally referred to a young woman or daughter. The modern Japanese simplified form is 嬢.
A woman (女) with the complex right side 襄, which looks like a person carrying something, can be remembered as a girl or daughter being carried or supported.
For ジョウ, imagine a young girl named Jo (ジョウ) who is always called 'Miss Jo' by her family. Jo -> ジョウ, and she is the daughter of the house.