DEPRECATED: use change-package with explicit tiers, which applies every dimension — and the platform fee every non-Mighty plan carries — in one call. Add, swap, or remove the included-credit bundle on the org's active Pro subscription without re-checkout. A null credit_tier removes the bundle (back to the $0 default); a set value adds (when none today) or swaps the existing bundle. UPGRADES (the credit value strictly increases; adding a bundle counts) charge the full price difference between the two tiers immediately — a flat difference, not a time-based Stripe proration — and grant the credit difference immediately; the renewal then bills the full new price. A declined difference charge returns HTTP 402 and reverts the change. Subscriptions carrying an active discount defer upgrades to the next cycle instead (the flat difference would ignore the coupon). DOWNGRADES and removals still use proration_behavior=none: the change — and the smaller monthly grant — take effect at the next cycle boundary, with no immediate charge or refund. Rejected with HTTP 409 while a cancellation is pending. Requires an active Pro subscription with a provisioned Stripe subscription.