    Sentence 1: The agreement between  architect Daniel  Libeskind —and|  representatives of developer Larry|  Silverstein gives architect David  Childs the lead role in developing]  the " Freedom Tower . "    Sentence 2: The collaboration gives  architect David Childs , who has  done extensive work with Silverstein]   the lead role in developing the  tower , which is to be the world 's|  tallest .