772. Costs incurred by mortgagee in defending title.

Costs incurred in asserting or defending the mortgagor's title to the mortgaged property are allowed1, but not costs incurred in defending the mortgagee's title to the mortgage against a third person2 unless provided for in the mortgage3. Similarly, the mortgagee may not charge the costs of defending proceedings for trespass brought by a third person unless those costs were incurred in protecting the title to the estate4. Where in proceedings properly taken to protect the security the mortgagee has already received costs from a third party, he is entitled to add any deficiency to his security