And be it enacted and declared, That the Powers given and granted by this Act, and by the said recited Act of the Tenth Year of the Reign of His said late Majesty, shall in no case be exercised to such an Extent as to deprive the Heir in Possession of any Entailed Lands and Estates in Scotland of more than Two Third Parts of the free yearly Rent or free yearly Proceeds of the same; and the Court of Session, in either Division thereof, is hereby authorized and required in each respective Case to give all necessary Orders for relieving the Heir in Possession from the Payment of more than such Two-third Parts of the said free yearly Rent or yearly Proceeds as aforesaid, by authorizing such Heir to retain any Excess beyond the same, from the Security or Provision, or Securities or Provisions on such Entailed Lands and Estates which shall be least entitled by the Law of Scotland to legal Preference.