What is the ruling on the actions of a sister who concealed her daughter's engagement from her sister, thinking that she would envy her, and insinuates to others that her sister envies her, and what is the ruling on the actions of the sister who began to adorn herself after the engagement and forgot what is permissible and what is forbidden?

The Shari'ah emphasizes love and harmony among Muslims, especially relatives. One should have a good opinion of a Muslim and not entertain ill thoughts without clear evidence. It is advised to be patient with your sister and pray for her, and to strive for reconciliation through wise individuals. If the estrangement continues, you should maintain ties with her and show kindness. Sustenance is in the hands of Allah, and what is decreed for the questioner's daughter will come to her. If the niece adorns herself (in a forbidden manner), this should be disapproved by advising her directly or through those close to her.