Your posting is confusing. A final say on what matter? Nothing was mandated in 1948. When Israel declared statehood on 14 May 1948, under UN resolution 181,the Palestinian Mandate expired. UN 181 allowed for the formation of two states, one Jewish and one Arab to be formed in Palestine. There was no mention of Jordan. nor should there have been. Jordan was already a sovereign, independent nation.
Report in Lebanon: Israel Air Force strikes Syria's Quneitra, 3 terror operatives killed (Haaretz)
from the article: A Palestinian peace plan Israelis can live with