Is it permissible to agree upon a irrevocably separated divorce (baynunah kubra) with the wife after a revocable divorce and the expiration of her waiting period ('iddah)?

If a woman is divorced with a revocable divorce, and her waiting period expires without her husband having taken her back, she becomes a stranger to him, and his divorce does not fall upon her due to the termination of the marital bond. Divorce does not fall upon a stranger, even if he made it conditional upon marriage, and this is what the majority of scholars have stipulated. Therefore, an agreement with a woman divorced with an irrevocable divorce for a major irrevocable divorce is not valid.