The families of hostages and their supporters participate in the ‘United for the Release the Hostages’ Rally in Paris Square after completing the four day march on March 2, in Jerusalem. Alexi J. Rosenfeld/Getty ImagesHamas has slashed the number of hostages it is willing to release during the first phase of a proposed ceasefire deal by more than half, an Israeli source close to the negotiations said.In its latest counterproposal, Hamas offered to release fewer than 20 hostages in exchange for a six-week ceasefire, more than halving the number of 40 hostages that has been the basis of…