Since, by definition, Biblical patriarchy presumes the LawWord of God is written on the heart of the true patriarch, the wife of such a man lives free of fear of abandonment, real or virtual. She will always be provided for and her needs met. This is the law of God.
Thus secure, such a wife would welcome the companionship of other godly women into the marriage. Rather than seeing other potential wives as competitors she will see them as blessings to her husband and herself.
For the Godly women who long for fulfillment in their calling to be wives and mothers, Biblical patriarchy means they may ask the true patriarch with whom they would be equally yoked, to take them as a wife. Whether he is already married or not is no longer the pertinent question but whether he is in fact a true patriarch, a mature man of Godly character who has shown that he has the LawWord of God written on his heart.