Aruch HaShulchan, Laws of Tzedakah, 251:14

Our rabbis, the authors of the Shulchan Aruch ,wrote about one who gives money to the tzedakah collector, that neither that person nor their descendants has any power over (the destiny of that money), and the community will do with (the money) what is right in the eyes of God and humanity. However, if the person designated money as tzedakah before it reached the collectors (and passed away), we give the money to the giver’s poor relatives because we assume the giver’s intention was to do so when the money was designated. But this is only when the giver has poor relatives; if all the relatives are wealthy at the time of the designation and subsequently become poor, we do not give (from the money) to them. And this is all if the designation was made only in front of the allocator of the tzedakah. But if the designation was made in front of the allocator and the people of the town, the people of the town shall do with the money as they desire. [Translation by AJWS]