The general rule in British Columbia is that a person under 19 cannot make a valid will. In B.C. nineteen is the age of majority.
But there are two exceptions. First, a person under 19 who is or has been married may make or revoke a will. Secondly, a "member of the Canadian Forces while placed on active service under the National Defence Act, or member of the naval, land or air force of any member of the British Commonwealth of Nations or any ally of Canada while on active service, or a mariner or seaman at sea or in the course of a voyage" may make or revoke a will even if he or she is under 19.
These provisions are set out in sections 5 and 7 of the Wills Act, RSBC 1996, c. 489.