Such an outcome might indeed be the best course of action, and the brothers of the two ladies had no objections whatsoever.
To become in-laws with His Highness the Crown Prince was a dream realized by few. They had undoubtedly benefited greatly from this unexpected turn of events.
While the Crown Prince hadn't explicitly promised any specific position for their sister, his assurance to welcome her into the royal residence was more than sufficient.
It was worth noting that the mere fact that their younger sisters had the opportunity to travel alongside the fifth princess and the others was due to the fifth princess exercising her special privileges. Given their family's relatively modest standing, becoming part of the Crown Prince's household was already a remarkable prospect.