Separation allowances for such dependents shall be paid on a basis of not more than twenty dollars per month to the spouse of such soldier, sailor or marine and not more than six dollars per month for each minor child, under sixteen years, of such soldier, sailor or marine, provided, if such soldier, sailor or marine has neither a spouse nor a child, but has actually and solely dependent upon him or her for support a father or brother who is unable to support himself by his own labors, or a mother or sister so solely and actually dependent, or, if such soldier, sailor or marine has such father, brother, mother or sister actually and solely dependent upon him in addition to a spouse or child or children or both, it shall be within the discretion of the Commissioner of Veterans Affairs to pay a separation allowance or separation allowances to such additional dependents, or to such spouse or children, or to both, provided no separation allowance paid to all dependents of one soldier, sailor or marine under the terms of this chapter shall amount in the aggregate to more than fifty dollars per month, and provided no person shall receive a separation allowance as a dependent of more than one soldier, sailor or marine.