According to the PMBOK Guide, a change request is a formal proposal to modify any document, deliverable, or baseline. Change requests are processed through the Perform Integrated Change Control process, which involves reviewing, analyzing, approving, or rejecting changes. The project manager should follow the change management process and work with procurement if needed to deal with the new requirement from the key stakeholder. The project manager should assess the impact of the change on the project scope, schedule, cost, quality, risk, and other aspects, and obtain approval from the appropriate authority before implementing the change. The project manager should also communicate the change to the subcontracting company and negotiate any contractual modifications if necessary. The project manager should not engage an arbitrator, add the change to the next sprint, or allocate resources to work on the new feature immediately, as these actions may bypass the change management process, create conflicts, or disrupt the project plan. References:

PMBOK Guide, 6th edition, pages 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153…

PMI-PBA Guide, pages 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53…