No release, waiver or conveyance of the estate so exempted shall be valid, unless the same is in writing, signed by the individual and his or her spouse, if he or she have one, or possession is abandoned or given pursuant to the conveyance; or if the exception is continued to a child or children without the order of a court directing a release thereof; but if a conveyance is made by an individual as grantor to his or her spouse, such conveyance shall be effectual to pass the title expressed therein to be conveyed thereby, whether or not the grantor in such conveyance is joined therein by his or her spouse. In any case where such release, waiver or conveyance is taken by way of mortgage or security, the same shall only be operative as to such specific release, waiver or conveyance; and when the same includes different pieces of land, or the homestead is of greater value than $15,000, the other lands shall first be sold before resorting to the homestead, and in case of the sale of such homestead, if any balance remains after the payment of the debt and costs, such balance shall, to the extent of $15,000 be exempt, and be applied upon such homestead exemption in the manner provided by law.