I've wronged my own child.
If it weren't for the imperial decree mandating the marriage, even if Prince Rong wanted to marry his granddaughter, Duke Zheng would have found a way to decline, but having been loyal to the emperor all his life, he had to reluctantly accept the imperial edict.
"Grandfather will arrange for someone to investigate. Don't worry, and I will inform you once there is news. As for the Crown Princess..." Duke Zheng thought of Su Xinyi, whose eyes had sparkled, "You were friends before, and now family by marriage, so maintain a good relationship with her. If there's anything inconvenient for the Crown Princess to handle, you can lend a hand."
Zhu Chanyi nodded, "I will listen to Grandfather."
"Go and talk with your mother, and as for your sister-in-law, don't mention it yet. Wait until I have seen your brother to discuss it further," Duke Zheng instructed his granddaughter.
Zhu Chanyi figured it would be so and smilingly agreed, then rose to leave.