If you make a change to your will in pen (or pencil, or using a typewriter) after you have signed the will, the change will probably not be valid. In British Columbia, any changes must be signed and witnessed in the same manner as a will. (See my earlier post on the formal requirements in British Columbia on making a will.) There is an exception if words are totally obliterated; then the will can take effect without obliterated words.
This is set out in section 17 of the Wills Act, RSBC 1996, c. 489, as follows:
17 (1) Subject to subsection (2), unless an alteration that is made in a will is made in accordance with the provisions of this Act governing the making of a will, the alteration has no effect, except to invalidate words or meanings that it renders no longer apparent.
(2) An alteration that is made in a will is validly made when the signature of the testator and the subscription of the witness or witnesses to the signature of the testator to the alteration are made
(a) in the margin or in some other part of the will opposite or near to the alteration, or
(b) at the end of or opposite to a memorandum referring to the alteration and written in some part of the will.
What happens after you die if you have made alterations in pen, but have not complied with the requirements of section 17(2). The will can still be admitted to probate, but without the changes. This will likely add some expense to the probate application, and may disappoint those who would have benefited by the changes if valid.