Workspace Enterprise -> Workspace Non-Profit Pricing?

I have a client who recently qualified for Non-Profit pricing for Google Workspace in Canada, and is currently on the normal Enterprise tier of Workspace.

While I've assisted clients before in configuration of both NP and standing Workspace configurations, I've never had one that's had to move from standing to discounted pricing, and we're struggling to understand the best way to do this.

Contacting support isn't much help - they seem to have communicated that we need to drop down to the lowest tier possible, switch over to non-profits at the free entry level tier, then move back up to the 70% discount, which seems nearly impossible given how much data they have in their Shared drives and email inboxes.

Hoping to get pointed in the right direction, but also not opposed to getting connected to Canadian organizations who've done this in the past and might have a space in assisting with this transfer