Read this: A samurai could divorce his wife for a variety of reasons with approval from a superior, but divorce was, while not entirely nonexistent, a rare event. A wife's failure to produce a son was cause for divorce, but adoption of a male heir was considered an acceptable alternative to divorce. A samurai could divorce for personal reasons, even if he simply did not like his wife, but this was generally avoided as it would embarrass the person who had arranged the marriage. A woman could also arrange a divorce, although it would generally take the form of the samurai divorcing her. After a divorce samurai had to return the betrothal money, which often prevented divorces.

What could samurai do instead of divorce if their wife couldn't produce a son?
What is the answer? (If it cannot be answered, return "unanswerable")
adoption of a male heir