And be it enacted, That no Heir of Entail in possession of an entailed Estate shall charge the same under this Act with any Provision to any younger Child or Children until he shall have applied for and obtained the Authority of the Court thereto in the Form and Manner herein-after provided ; and such Application to the Court shall set forth in a Schedule to be annexed thereto the specific Portion of the Estate which it is proposed to include in such Bonds and Dispositions in Security.