Evidence of a whole or entire dependency shall not be required. The mother or father shall be considered dependent for the purposes of the act when it is established as a fact that the mother or father of a deceased veteran did not have sufficient means from all sources for a reasonable livelihood at the time of the death of the veteran or at any time thereafter and on or before January 2, 1935. In those cases where because of continued and unexplained absence for seven years the veteran is declared deceased under section 312(a) of the Act as amended May 29, 1928, the mother or father shall be considered dependent when it is established that the mother or father did not have sufficient means from all sources for a reasonable livelihood at the beginning of such 7-year period or at any time thereafter and before the expiration of such period.