An important distinction is distinguishing between the legislative process and the appropriations process. The legislative process is requesting legislative authority to purchase up to the maximum allowable share that Canada could have under the allocation formula. The appropriation, which is budget 2017, is only speaking to the $199 million. If the decision was taken by the government to make additional share purchases at that point an additional appropriation would be requested by the government and that would be brought back to Parliament.
On November 21st, 2017. See this statement in context.