(1)  A registered mortgage or encumbrance may be varied in any of the following ways:

(a) the amount secured by the mortgage or encumbrance may be increased or reduced;

(b) the rate of interest may be increased or reduced;

(c) the term or currency of the mortgage or encumbrance may be shortened, extended, or renewed;

(d) the covenants, conditions, and powers contained or implied in the mortgage or encumbrance may be varied, negatived, or added to –

by an instrument in an approved form, executed by the respective parties or their successors in title, and registered under this Act.

(2)  Notwithstanding anything in subsection (1) , it is not necessary for –

(a) a mortgagor or encumbrancer to execute an instrument which reduces; or

(b) a mortgagee or encumbrancee to execute an instrument which increases –

the mortgage debt, or the money payable under an encumbrance, or the rate of interest payable under a mortgage or encumbrance, without otherwise varying the mortgage or encumbrance.

(3)  An instrument under this section varying a mortgage or encumbrance affecting land subject to a subsequent mortgage or encumbrance is not binding on a subsequent mortgagee or encumbrancee unless the subsequent morgagee or encumbrancee has consented to the variation in writing on that instrument, but that consent renders the instrument binding on the subsequent mortgagee or encumbrancee so consenting, and is binding on all persons who may subsequently derive from the subsequent mortgagee or encumbrancee any interest in the mortgaged or encumbered property.