Can we go for enhanced commissioning after start of operation

Our client have decided suddenly to go for enhanced commissioning. The construction is complete and the building starts to operate. The fundamental commissioning has been already done. Operation staff have been trained on the most of systems O&M. Trainings on the rest of systems are scheduled as well. All control drawings, systems single line diagrams, and system manuals and O&M are available. What is only missing and the CxA of enhanced commissioning should be involved in is the design review which already reviewed by the project general consultant and checked by the client with sharing with LEED team for advice. My question is, can we pursue EAc3 at this stage of the project? can the client appoint CxA for enhanced commissioning to do the following: 1. review the approvals of systems transmittals to check if everything is ok and make a design review report. 2. Compile the manuals of all systems and put the schedule of O&M 3. Perform the post-occupancy commissioning verification? Thank you