War-game a pricing grandfather clause before eligibility windows, sunset dates, and exception talk tracks harden into how every legacy account gets protected.
Grandfather clauses fail when the window invents permanence the contract never had, when eligibility dual-counts the same account as protected and as migrated, when sales still promises "forever" in private Slack, and when finance cannot show who owns margin after forced renewals. A neat clause draft is not evidence.
Freeze one clause
State the proposed eligibility rules, which cohorts and plan codes it covers, who owns sunset notices and audit, what success looks like after two quarters of margin integrity and complaint rate, and the kill criteria if shadow promises or eligibility disputes past a named threshold. Attach the cohort list, sample contracts, notice drafts, and the measured path from eligibility check to posted renewal. If pricing, legal, and success disagree on whether the clause buys trust or just deferred cliffs, reconcile before seating.
Name the decision you will make if the war game finds nothing new, and the hold criteria if any cohort still lacks a named owner or a verified notice path.
Hostile seats
- Legacy customer. Fear that "grandfathered" still means a quiet sunset six months later.
- Finance. Margin math that looks clean while protected cohorts cannot be listed.
- Sales. Forever language that invents permanence the clause never wrote.
- Legal. Notice periods that still host retired definitions.
- Skeptic. The claim that looks strongest and is least sourced.
Optional success seat if win-back after sunset binds the form. Same pack for every seat.
Private pass
Feed Pingpong the clause draft and exhibits. First pass steelmans the eligibility. Later passes attack from the seats above. Final pass turns surviving objections into clearer windows, a published sunset path, or a hold. Delete invented "customers already understand this" claims and dual-counted protected rates.
Force a day-after narrative: what happens if a large account screenshots mismatched pricing, if sales still teaches forever language, or if finance cannot list the protected cohort. If those stories are stronger than your mitigation plan, fix the package before you publish it. Separate a pricing grandfather clause from a legacy plan sunset or a pricing change so each decision stays testable.
Ask every seat to mark which steps are optional in practice. Optional eligibility audits become skipped within a month if nobody names the owner and the time box. Related: war-game a packaging change, war-game a pricing floor, pretend you are the customer success lead, and the war-game decisions hub. Process: how to run a Pingpong.