Are the maternal uncles of the husband and wife Mahaarim (non-marriageable relatives) to their daughters?
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
The maternal uncles of the parents (husband and wife) are maternal uncles to their children and grandchildren, therefore, these maternal uncles are Mahaarim to those daughters.
Allaah Knows best.
You can search for fatwa through many choices