Answered by Ustadh Tabraze Azam
Question: Assalam alaykum,
1. Are my grandparents siblings mahram to me?
2. Are my father-in-law’s brothers (uncles-in-law) mahram to me?
Answer: Assalamu alaikum wa rahmatullah,
A person is from your unmarriageable kin (mahram) when they are immediately related to you, (a) by blood (qaraba), (b) through marriage (sihriyya) or (c) through nursing (rada`a). For details, please see: Who is Mahram
1. Yes, your great-uncles, namely, your grandfather’s brothers, are from your unmarriageable kin (mahram).
2. No, your father-in-law’s brothers are not from your unmarriageable kin (mahram).
[Qadri Pasha, al-Ahkam al-Shar`iyya fi al-Ahwal al-Shakhsiyya (Article 22)]
And Allah Most High alone knows best.
Checked & Approved by Shaykh Faraz Rabbani