You were doing fine until right there.
I'm pretty sure that's illegal.
e.g. SNC-Lavalin got caught giving their money to donate to the Liberal Party of Canada.
A few years earlier a Toronto law firm got caught doing the same thing, although I can't find it at the moment.The investigation reveals that over a period of more than five years between 2004 and 2009, 18 former SNC-Lavalin employees, directors and some spouses contributed nearly $110,000 to the federal Liberals, including to four party leadership campaigns and four riding associations in Quebec.
According to the letter, the investigation found that SNC-Lavalin reimbursed all of those individual donations — a practice forbidden under the Canada Elections Act.
https://www.cbc.ca/news/politics/snc...ions-1.5114537
There may be some wording you can use to get around it. Inform everyone before the purchase and again on the receipt that a portion of their purchase is going to the Party. Maybe. But you can't say a portion of your profit is going as a donation. A lawyer might know how to word it.
You can sell people parts at inflated prices, such as a Make Trudeau A Drama Teacher Again hat or magazine for ~$30 ($30 = $10 hat + $20 donation. Anything less than $20 might not get a tax receipt, I don't recall). That would be similar to $500-a-head fundraising dinners, where $450 is donated to the Party, and $50 goes to the food/venue.