I have seen families making fun of low income individuals and also the respect given to higher income family members. Upto what extent a family should know the income of individuals and, what are the pros and cons. Seeking answers according to dharma and duties to be followed in such situations
The amount of wealth one possesses is one of the many things that a householder must keep secret.
See the following verses from Chapter 3 of the Daksha Smriti:
Iniquitous deeds are, again, [the following : ] Falsehood, knowing another's wife, taking forbidden food, knowing a woman who should not be known, drinking what should not be drunk, theft, committing injury, doing works not sanctioned in the S'ruti, transgression of a friend's duty, these are nine improper deeds. One should avoid them all.
Longevity, wealth, weakness of a house, counsel, sexual intercourse, medicine, austerity, charity, and honour, these nine should be carefully kept secret.
Freedom from a disease, satisfaction of a debt, gift, study, sale, giving away a daughter in marriage, dedication of a bull, secret sin, and the act of not being censured by others, these nine should be publicly done by a householder. (verses 8-14)
From this injunction we can infer that there is no harm in not telling others what one's income is.