I offer premium member subscriptions and I’d like to offer a discount to members of partnered organizations.

What is the best way to go about this? I’ve considered the following:

1. Discounted plan only visible to members of certain Group/Organization (unsure if this is doable in the Paid Levels app)
2. Discount code manually sent to users who send proof of membership (not efficient/scalable)
3. Partner Org’s Membership IDs used as the discount code for my site (most advanced and would require coding I can’t do yet)