The Ruling on Wearing the Abaya in Front of Mahrams and Others

This is a letter we received, which says: I am the believing sister (H. A. S.) from Iraq. I thank the program "Light on the Path" and I thank the scholars. I ask you: Is it permissible for me to wear my abaya in front of my father, my mother, my brother, and my sisters' husbands? I have not worn my abaya in front of them until now. I hope you will be kind enough to answer my question, with much thanks to you?
Answer: The obligatory thing is to observe hijab in front of non-mahrams, such as your sisters' husbands, O questioner. As for your father and your brothers, these are mahrams. The father is a mahram, and the brothers are mahrams. But the sisters' husbands are not mahrams. Your sister's husband, as well as your husband's uncle and your husband's brother, none of them are mahrams. As for your brothers, your father, your paternal grandfather, your paternal uncles, and your maternal uncles, these are mahrams. Likewise, the husband's father and the husband's son are mahrams. But the husband's brother, the husband's uncle, and his maternal uncle are not mahrams. Similarly, the sister's husband is not a mahram. So you must observe hijab in front of him with the abaya or something other than the abaya, with the jilbab, with the khimar on your face and head, and the qamis on your body. The point is to observe hijab with whatever is available, whether an abaya or otherwise. This is what is prescribed. Yes.