IIRC, when funds were being collected, there was a statement funds would be used on effectively a FIFO (first in, first out) basis.

Unused funds would be returned to the newest contributors (up to the amounts they contributed); the last money in got refunded to the last contributor first, working backwards up the list.

Of course, if someone wanted to direct that their specific refund be sent to a worthy cause (or even an unworthy cause), that should be OK, too.