Is breaking a voluntary fast obligatory or merely recommended if guests arrive, especially if they are one's parents and siblings?

If a guest arrives while one is observing a voluntary fast, and the fasting person believes that honoring their guest cannot be fully achieved without breaking their fast, then it is recommended for them to break the fast and make up for it whenever it becomes easy for them. It is not disliked to break a voluntary fast for an excuse; rather, it is recommended, due to the Prophet’s (peace be upon him) saying: "And indeed, your visitor has a right over you," and "Whoever believes in Allah and the Last Day should honor his guest." However, if refraining (from breaking the fast) does not cause difficulty for either party, then it is better not to break the fast.