Make the Change – sometimes you lose and have to make the change.
Be sure to save all of your original work, document the impact on all levels, provide a new schedule, budget, scope, SLA’s, etc.
Keep and eye on execution throughout and if it turns out it was a better plan, acknowledge it.
If you were right, be gracious in your updates as you need switch back to your original path.
Make the final outcome and deltas part of your Lessons Learned and don’t be afraid to revisit on the next project that gets “adjusted” by someone else besides you, the project planner and manager.