Why do people in some areas need an "A" in their names, such as brother, sister, grandmother and so on?

This word is a prefix.

As an affix, it is attached to the surname, first name, ranking or the names of some relatives, often with the meaning of intimacy, and is often used in dialects.

Father. The father's upbringing of his children is like caring for the family in Qufu. In Wu-speaking areas, ABBA is a title for father. Wu dialect area is mainly located in Jiangsu, Zhejiang and Shanghai, including a few areas in neighboring provinces. In the middle of Wu dialect area, ABBA is a very common name for father.

Elder brother: Address for elder brother, especially in Cantonese.

Sister: The ancients often called my sister "Sister", but now in southern China, I call my sister "Sister". For example, in northern Wu dialect, it is pronounced as ah tsia.

Adi: "Adi" is commonly used in southern areas, such as Wu dialect, Cantonese and Minnan dialect, but less used in northern areas.

A-mei: A-mei is another name for the younger generation of Hakka elders, regardless of gender and age. It can be for parents of children, grandparents of grandchildren, uncles of nephews, parents-in-law of son-in-law, etc. So we can see that parents in their eighties and nineties affectionately call their children in their sixties and seventies "A-mei". Whether you are a middle-aged person, an old woman or a three-year-old child, as long as your elders are still there, they can call you "A-mei".

Auntie: Auntie, for short, is a modern title for women, such as aunt sweeping the floor and aunt cooking, but it is usually a kinship title, referring to the mother's sister or younger sister. In some places, menstruation refers to the mother's sister, and the mother's sister is called aunt, aunt or aunt. In ancient times, it was called obedient mother.

I hope it can help you solve the problem.