Complex sentence: At very large occasions, such as wedding or funeral banquets, the tamada is chosen in advance by the family, who ask a relative or friend who is known to be a good tamada to lead the supra.
Split into simpler sentences: At very large occasions, such as wedding or funeral banquets, the tamada is chosen in advance by the family. They ask a relative or friend who is known to be a good tamada, to lead the supra.