Compensation shall be payable under this section¹ to or on account of any child, brother, or sister, only if and while such child, brother, or sister, is under the age of eighteen unless such child, brother or sister is dependent because of disability when compensation shall continue or be paid during such disability of a child, brother or sister over eighteen years of age or unless such child is enrolled as a full-time student in any accredited educational institution when compensation shall continue until such student becomes twenty-three. No compensation shall be payable under this section to a widow, unless she was living with her deceased husband at the time of his death, or was then actually dependent upon him and receiving from him a substantial portion of her support. No compensation shall be payable under this section to a widower, unless he be incapable of self-support at the time of his wife's death and be at such time dependent upon her for support. If members of decedent's household at the time of his death, the terms “child” and “children” shall include step-children, adopted children and children to whom he stood in loco parentis, and children of the deceased and shall include posthumous children. Should any dependent of a deceased employe die or remarry, or should the widower become capable of self-support, the right of such dependent or widower to compensation under this section shall cease except that if a widow remarries, she shall receive one hundred four weeks compensation at a rate computed in accordance with clause (2)² in a lump sum after which compensation shall cease: Provided, however, That if, upon investigation and hearing, it shall be ascertained that the widow or widower is living with a man or woman, as the case may be, in meretricious relationship and not married, or the widow living a life of prostitution, the board may order the termination of compensation payable to such widow or widower. If the compensation payable under this section to any person shall, for any cause, cease, the compensation to the remaining persons entitled thereunder shall thereafter be the same as would have been payable to them had they been the only persons entitled to compensation at the time of the death of the deceased.