My comment was pretty vague but yes, I was referring to the funding for this coming from external sources including the provinces program for lowering DC.
You may be choosing to simplify the description of the program for brevity, but this isn't an agreement to reduce DC by 50%: https://www.ontario.ca/page/development-charge-reduction-program
It's a funding program that needs to be applied to, and the pool of money is handed out based on the criteria on that page.
None of this prevents the province from ordering a municipality to lower their DCs based on their whims. That's a fear in the municipal asset management world throughout the country: capacity upgrades have been delayed and delayed to keep spending down, and with the push for housing the provinces are targeting DCs and are like, "too bad lol".
Eta: I would encourage people to read this: https://www.calgary.ca/emergencies/feeder-main-repair/bearspaw-feeder-main-independent-review.html