Is it permissible for a man to be married simultaneously to a woman (the paternal aunt) and her brother's daughter, with another wife between them, such that the paternal aunt is his first wife, the other woman is his second wife, and the paternal aunt's brother's daughter is his third wife?

The Sharia has forbidden combining a woman with her paternal aunt (ʿammah) and a woman with her maternal aunt (khālah). The presence of another unrelated woman does not affect this prohibition. A man is not permitted to marry the niece unless the aunt has passed away, or he has divorced her with a final, irrevocable divorce (ṭalāq bā’in), or her waiting period (ʿiddah) has ended.