Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 79, § 33

If mortgagors or mortgagees begin or become parties to such proceedings, entire damages shall, upon final judgment, be assessed for the property taken, and such portion thereof as is equal to the amount then unpaid thereon shall be ordered to be paid to every mortgagee who is a party, in the order of his mortgage, and the remainder to the mortgagor; and separate judgment shall be entered accordingly for each mortgagee, who shall hold his judgment in trust, first, with any proceeds realized thereon, to satisfy his mortgage debt, and, after such debt is in any way satisfied, to assign the judgment or pay over any remainder of the proceeds to the mortgagor or other person entitled thereto.