What is the ruling on a woman adorning herself for her husband's female relatives, and what are the limits of the Shar'i dress in front of them?

There is no harm for a woman to adorn herself with what is permissible and to appear with her adornment before her husband's sisters. As for a woman's awrah (intimate parts) before her fellow women, there is a detailed explanation for that. However, one must be careful not to display her adornment before her husband's brothers or to be alone with any of them, as many people are lenient in this matter, which becomes a cause for fitnah (temptation/strife).