After some thinking... I think the whole affair went differently. No money was actually send, because it would be too much hassle. Instead, the local lord was ordered to allocate a portion of revenue earmarked for the crown to support the orphanage.
This cant happen. The kings cant give a reward he himself promised by ordering someone else to give his money.
There's no parallel with president and mayor, because the money the president and mayor use are the money of the country, which is the money of the people.
A king has his own tresury, and a noble also has his own different tresury. A king take taxes from the noble to run the country and do things with his own money.
A king who own someone a gift would not and can not ask a noble to give the reward. Not only would this undermine his own autority and his honor, but it would literaly put him in the debt of said noble.
It make no sense at all.
There's no hassle, kings were doing this all the time. Even Louis XIV who was renowed around the world and had people comming from everywhere to see him gave the gift by himself or by sending his personal men.
Doing this not only bolster his popularity, but even helped him reduce the authority of nobles.