Complex sentence: The children lived in this comfortable establishment until they were about seven years old; then they began to accompany their parents for important occasions, and by their teens they were with the king and queen much of the time.
Split into simpler sentences: The children lived in this comfortable establishment until they were about seven years old; then they began to accompany their parents, if at first only on important occasions. By their teens they were with the king and queen much of the time.